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fix memory leak in get_task_name()

PATCH Superseded Andrea Claudi 5 participants 12 messages Mar 2, 2022 – Mar 9, 2022

Subsystems (3)
Networking Network drivers Library code

v2 of 3 Superseded Latest is v3 →

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Andrea Claudi

author
#0 lore raw

v2 cover fix memory leak in get_task_name()

This series fixes some memory leaks related to the usage of the get_task_name() function from lib/fs.c.

Patch 2/2 addresses a coverity warning related to this memory leak, making the code a bit more readable by humans and coverity.

Changelog:
----------
v1 -> v2
- on Stephen's suggestion, drop asprintf() and use a local var for path; additionally drop %m from fscanf to not allocate memory, and resort to a param to return task name to the caller.
- patch 2/3 of the original series is no more needed.

Andrea Claudi (2):
lib/fs: fix memory leak in get_task_name()
rdma: make RES_PID and RES_KERN_NAME alternative to each other

 include/utils.h |  2 +-
 ip/iptuntap.c   | 17 ++++++++++-------
 lib/fs.c        | 20 ++++++++++----------
 rdma/res-cmid.c | 18 +++++++++---------
 rdma/res-cq.c   | 17 +++++++++--------
 rdma/res-ctx.c  | 16 ++++++++--------
 rdma/res-mr.c   | 15 ++++++++-------
 rdma/res-pd.c   | 17 +++++++++--------
 rdma/res-qp.c   | 16 ++++++++--------
 rdma/res-srq.c  | 17 +++++++++--------
 rdma/stat.c     | 14 +++++++++-----
 11 files changed, 90 insertions(+), 79 deletions(-)
Signature · 1 line
2.35.1
author
#1 lore raw

PATCH v2 1/2 lib/fs: fix memory leak in get_task_name()

asprintf() allocates memory which is not freed on the error path of get_task_name(), thus potentially leading to memory leaks.

Rework get_task_name() and avoid asprintf() usage and memory allocation, returning the task string to the caller using an additional char* parameter.

Fixes 81bfd01a4c9e ("lib: move get_task_name() from rdma")
Signed-off-by Andrea Claudi <[email protected]>
---
 include/utils.h |  2 +-
 ip/iptuntap.c   | 17 ++++++++++-------
 lib/fs.c        | 20 ++++++++++----------
 rdma/res-cmid.c |  8 +++++---
 rdma/res-cq.c   |  8 +++++---
 rdma/res-ctx.c  |  7 ++++---
 rdma/res-mr.c   |  7 ++++---
 rdma/res-pd.c   |  8 +++++---
 rdma/res-qp.c   |  7 ++++---
 rdma/res-srq.c  |  7 ++++---
 rdma/stat.c     |  5 ++++-
 11 files changed, 56 insertions(+), 40 deletions(-)
include/utils.h +1 -1
index b6c468e9..81294488 100644
@@ -307,7 +307,7 @@ char *find_cgroup2_mount(bool do_mount);
 __u64 get_cgroup2_id(const char *path);
 char *get_cgroup2_path(__u64 id, bool full);
 int get_command_name(const char *pid, char *comm, size_t len);
-char *get_task_name(pid_t pid);
+int get_task_name(pid_t pid, char *name);
 
 int get_rtnl_link_stats_rta(struct rtnl_link_stats64 *stats64,
 			    struct rtattr *tb[]);
ip/iptuntap.c +10 -7
index 385d2bd8..2ae6b1a1 100644
@@ -321,14 +321,17 @@ static void show_processes(const char *name)
 			} else if (err == 2 &&
 				   !strcmp("iff", key) &&
 				   !strcmp(name, value)) {
-				char *pname = get_task_name(pid);
-
-				print_string(PRINT_ANY, "name",
-					     "%s", pname ? : "<NULL>");
+				SPRINT_BUF(pname);
+
+				if (get_task_name(pid, pname)) {
+					print_string(PRINT_ANY, "name",
+						     "%s", "<NULL>");
+				} else {
+					print_string(PRINT_ANY, "name",
+						     "%s", pname);
+				}
 
-				print_uint(PRINT_ANY, "pid",
-					   "(%d)", pid);
-				free(pname);
+				print_uint(PRINT_ANY, "pid", "(%d)", pid);
 			}
 
 			free(key);
lib/fs.c +10 -10
index f6f5f8a0..03df0f6a 100644
@@ -342,25 +342,25 @@ int get_command_name(const char *pid, char *comm, size_t len)
 	return 0;
 }
 
-char *get_task_name(pid_t pid)
+int get_task_name(pid_t pid, char *name)
 {
-	char *comm;
+	char path[PATH_MAX];
 	FILE *f;
 
 	if (!pid)
-		return NULL;
+		return -1;
 
-	if (asprintf(&comm, "/proc/%d/comm", pid) < 0)
-		return NULL;
+	if (snprintf(path, sizeof(path), "/proc/%d/comm", pid) >= sizeof(path))
+		return -1;
 
-	f = fopen(comm, "r");
+	f = fopen(path, "r");
 	if (!f)
-		return NULL;
+		return -1;
 
-	if (fscanf(f, "%ms\n", &comm) != 1)
-		comm = NULL;
+	if (fscanf(f, "%s\n", name) != 1)
+		return -1;
 
 	fclose(f);
 
-	return comm;
+	return 0;
 }
rdma/res-cmid.c +5 -3
index bfaa47b5..3475349d 100644
@@ -159,8 +159,11 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -199,8 +202,7 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-cq.c +5 -3
index 9e7c4f51..5ed455ea 100644
@@ -84,8 +84,11 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -123,8 +126,7 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-ctx.c +4 -3
index 30afe97a..fbd52dd5 100644
@@ -18,8 +18,11 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
 		return MNL_CB_ERROR;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -48,8 +51,6 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-mr.c +4 -3
index 1bf73f3a..6a59d9e4 100644
@@ -47,8 +47,11 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -87,8 +90,6 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-pd.c +5 -3
index df538010..a51bb634 100644
@@ -34,8 +34,11 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
 			nla_line[RDMA_NLDEV_ATTR_RES_UNSAFE_GLOBAL_RKEY]);
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -76,8 +79,7 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-qp.c +4 -3
index a38be399..575e0529 100644
@@ -146,8 +146,11 @@ static int res_qp_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -179,8 +182,6 @@ static int res_qp_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-srq.c +4 -3
index 3038c352..945109fc 100644
@@ -174,8 +174,11 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
 		return MNL_CB_ERROR;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 	if (rd_is_filtered_attr(rd, "pid", pid,
 				nla_line[RDMA_NLDEV_ATTR_RES_PID]))

@@ -228,8 +231,6 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/stat.c +4 -1
index adfcd34a..a63b70a4 100644
@@ -248,8 +248,11 @@ static int res_counter_line(struct rd *rd, const char *name, int index,
 		return MNL_CB_OK;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 	if (rd_is_filtered_attr(rd, "pid", pid,
 				nla_line[RDMA_NLDEV_ATTR_RES_PID]))
Signature · 1 line
2.35.1
author
#11 lore raw

PATCH v2 2/2 rdma: make RES_PID and RES_KERN_NAME alternative to each other

In reply to Andrea Claudi

RDMA_NLDEV_ATTR_RES_PID and RDMA_NLDEV_ATTR_RES_KERN_NAME cannot be set together, as evident for the fill_res_name_pid() function in the kernel infiniband driver. This commit makes this clear at first glance, using an else branch for the RDMA_NLDEV_ATTR_RES_KERN_NAME case.

This also helps coverity to better understand this code and avoid producing a bogus warning complaining about mnl_attr_get_str overwriting comme, and thus leaking the storage that comm points to.

Signed-off-by Andrea Claudi <[email protected]>
---
 rdma/res-cmid.c | 10 ++++------
 rdma/res-cq.c   |  9 ++++-----
 rdma/res-ctx.c  |  9 ++++-----
 rdma/res-mr.c   |  8 ++++----
 rdma/res-pd.c   |  9 ++++-----
 rdma/res-qp.c   |  9 ++++-----
 rdma/res-srq.c  | 10 +++++-----
 rdma/stat.c     |  9 +++++----
 8 files changed, 34 insertions(+), 39 deletions(-)
rdma/res-cmid.c +4 -6
index 3475349d..3abc5b42 100644
@@ -164,6 +164,10 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
 		if (!get_task_name(pid, b))
 			comm = b;
+	} else if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]) {
+		/* discard const from mnl_attr_get_str */
+		comm = (char *)mnl_attr_get_str(
+			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -176,12 +180,6 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
 				nla_line[RDMA_NLDEV_ATTR_RES_CM_IDN]))
 		goto out;
 
-	if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]) {
-		/* discard const from mnl_attr_get_str */
-		comm = (char *)mnl_attr_get_str(
-			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
-	}
-
 	open_json_object(NULL);
 	print_link(rd, idx, name, port, nla_line);
 	res_print_uint(rd, "cm-idn", cm_idn,
rdma/res-cq.c +4 -5
index 5ed455ea..e691f21f 100644
@@ -89,6 +89,10 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
 		if (!get_task_name(pid, b))
 			comm = b;
+	} else if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]) {
+		/* discard const from mnl_attr_get_str */
+		comm = (char *)mnl_attr_get_str(
+			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -106,11 +110,6 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
 				nla_line[RDMA_NLDEV_ATTR_RES_CTXN]))
 		goto out;
 
-	if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME])
-		/* discard const from mnl_attr_get_str */
-		comm = (char *)mnl_attr_get_str(
-			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
-
 	open_json_object(NULL);
 	print_dev(rd, idx, name);
 	res_print_uint(rd, "cqn", cqn, nla_line[RDMA_NLDEV_ATTR_RES_CQN]);
rdma/res-ctx.c +4 -5
index fbd52dd5..e300f605 100644
@@ -23,6 +23,10 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
 		if (!get_task_name(pid, b))
 			comm = b;
+	} else if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]) {
+		/* discard const from mnl_attr_get_str */
+		comm = (char *)mnl_attr_get_str(
+			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -36,11 +40,6 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
 				nla_line[RDMA_NLDEV_ATTR_RES_CTXN]))
 		goto out;
 
-	if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME])
-		/* discard const from mnl_attr_get_str */
-		comm = (char *)mnl_attr_get_str(
-			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
-
 	open_json_object(NULL);
 	print_dev(rd, idx, name);
 	res_print_uint(rd, "ctxn", ctxn, nla_line[RDMA_NLDEV_ATTR_RES_CTXN]);
rdma/res-mr.c +4 -4
index 6a59d9e4..f3a86cac 100644
@@ -52,6 +52,10 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
 		if (!get_task_name(pid, b))
 			comm = b;
+	} else if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]) {
+		/* discard const from mnl_attr_get_str */
+		comm = (char *)mnl_attr_get_str(
+			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -70,10 +74,6 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
 				nla_line[RDMA_NLDEV_ATTR_RES_PDN]))
 		goto out;
 
-	if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME])
-		/* discard const from mnl_attr_get_str */
-		comm = (char *)mnl_attr_get_str(
-			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
 	open_json_object(NULL);
 	print_dev(rd, idx, name);
 	res_print_uint(rd, "mrn", mrn, nla_line[RDMA_NLDEV_ATTR_RES_MRN]);
rdma/res-pd.c +4 -5
index a51bb634..7ab3ac6b 100644
@@ -39,6 +39,10 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
 		if (!get_task_name(pid, b))
 			comm = b;
+	} else if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]) {
+		/* discard const from mnl_attr_get_str */
+		comm = (char *)mnl_attr_get_str(
+			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -58,11 +62,6 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
 				nla_line[RDMA_NLDEV_ATTR_RES_PDN]))
 		goto out;
 
-	if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME])
-		/* discard const from mnl_attr_get_str */
-		comm = (char *)mnl_attr_get_str(
-			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
-
 	open_json_object(NULL);
 	print_dev(rd, idx, name);
 	res_print_uint(rd, "pdn", pdn, nla_line[RDMA_NLDEV_ATTR_RES_PDN]);
rdma/res-qp.c +4 -5
index 575e0529..d15522e8 100644
@@ -151,17 +151,16 @@ static int res_qp_line(struct rd *rd, const char *name, int idx,
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
 		if (!get_task_name(pid, b))
 			comm = b;
+	} else if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]) {
+		/* discard const from mnl_attr_get_str */
+		comm = (char *)mnl_attr_get_str(
+			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,
 				nla_line[RDMA_NLDEV_ATTR_RES_PID]))
 		goto out;
 
-	if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME])
-		/* discard const from mnl_attr_get_str */
-		comm = (char *)mnl_attr_get_str(
-			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
-
 	open_json_object(NULL);
 	print_link(rd, idx, name, port, nla_line);
 	res_print_uint(rd, "lqpn", lqpn, nla_line[RDMA_NLDEV_ATTR_RES_LQPN]);
rdma/res-srq.c +5 -5
index 945109fc..2944ee4a 100644
@@ -179,7 +179,12 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
 		if (!get_task_name(pid, b))
 			comm = b;
+	} else if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]) {
+		/* discard const from mnl_attr_get_str */
+		comm = (char *)mnl_attr_get_str(
+			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
 	}
+
 	if (rd_is_filtered_attr(rd, "pid", pid,
 				nla_line[RDMA_NLDEV_ATTR_RES_PID]))
 		goto out;

@@ -212,11 +217,6 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
 			MNL_CB_OK)
 		goto out;
 
-	if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME])
-		/* discard const from mnl_attr_get_str */
-		comm = (char *)mnl_attr_get_str(
-			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
-
 	open_json_object(NULL);
 	print_dev(rd, idx, name);
 	res_print_uint(rd, "srqn", srqn, nla_line[RDMA_NLDEV_ATTR_RES_SRQN]);
rdma/stat.c +5 -4
index a63b70a4..fe66f4d0 100644
@@ -253,15 +253,16 @@ static int res_counter_line(struct rd *rd, const char *name, int index,
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
 		if (!get_task_name(pid, b))
 			comm = b;
+	} else if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]) {
+		/* discard const from mnl_attr_get_str */
+		comm = (char *)mnl_attr_get_str(
+			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
 	}
+
 	if (rd_is_filtered_attr(rd, "pid", pid,
 				nla_line[RDMA_NLDEV_ATTR_RES_PID]))
 		return MNL_CB_OK;
 
-	if (nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME])
-		comm = (char *)mnl_attr_get_str(
-			nla_line[RDMA_NLDEV_ATTR_RES_KERN_NAME]);
-
 	mnl_attr_for_each_nested(nla_entry, qp_table) {
 		struct nlattr *qp_line[RDMA_NLDEV_ATTR_MAX] = {};
Signature · 1 line
2.35.1
#2 lore raw

Re: [PATCH iproute2 v2 1/2] lib/fs: fix memory leak in get_task_name()

In reply to Andrea Claudi
Quoted 2 lines · Andrea Claudi

asprintf() allocates memory which is not freed on the error path of get_task_name(), thus potentially leading to memory leaks.

Not really, memory is released when the application exits, which is the case here.

Quoted 6 lines

Rework get_task_name() and avoid asprintf() usage and memory allocation, returning the task string to the caller using an additional char* parameter.

Fixes 81bfd01a4c9e ("lib: move get_task_name() from rdma")

As I was told before, in netdev Fixes means that it is a bug that affects users. This is not the case here.

Quoted 14 lines
Signed-off-by Andrea Claudi <[email protected]>
---
 include/utils.h |  2 +-
 ip/iptuntap.c   | 17 ++++++++++-------
 lib/fs.c        | 20 ++++++++++----------
 rdma/res-cmid.c |  8 +++++---
 rdma/res-cq.c   |  8 +++++---
 rdma/res-ctx.c  |  7 ++++---
 rdma/res-mr.c   |  7 ++++---
 rdma/res-pd.c   |  8 +++++---
 rdma/res-qp.c   |  7 ++++---
 rdma/res-srq.c  |  7 ++++---
 rdma/stat.c     |  5 ++++-
 11 files changed, 56 insertions(+), 40 deletions(-)

Honestly, I don't see any need in both patches.

Thanks

Quoted 288 lines
include/utils.h +1 -1
index b6c468e9..81294488 100644
@@ -307,7 +307,7 @@ char *find_cgroup2_mount(bool do_mount);
 __u64 get_cgroup2_id(const char *path);
 char *get_cgroup2_path(__u64 id, bool full);
 int get_command_name(const char *pid, char *comm, size_t len);
-char *get_task_name(pid_t pid);
+int get_task_name(pid_t pid, char *name);
 
 int get_rtnl_link_stats_rta(struct rtnl_link_stats64 *stats64,
 			    struct rtattr *tb[]);
ip/iptuntap.c +10 -7
index 385d2bd8..2ae6b1a1 100644
@@ -321,14 +321,17 @@ static void show_processes(const char *name)
 			} else if (err == 2 &&
 				   !strcmp("iff", key) &&
 				   !strcmp(name, value)) {
-				char *pname = get_task_name(pid);
-
-				print_string(PRINT_ANY, "name",
-					     "%s", pname ? : "<NULL>");
+				SPRINT_BUF(pname);
+
+				if (get_task_name(pid, pname)) {
+					print_string(PRINT_ANY, "name",
+						     "%s", "<NULL>");
+				} else {
+					print_string(PRINT_ANY, "name",
+						     "%s", pname);
+				}
 
-				print_uint(PRINT_ANY, "pid",
-					   "(%d)", pid);
-				free(pname);
+				print_uint(PRINT_ANY, "pid", "(%d)", pid);
 			}
 
 			free(key);
lib/fs.c +10 -10
index f6f5f8a0..03df0f6a 100644
@@ -342,25 +342,25 @@ int get_command_name(const char *pid, char *comm, size_t len)
 	return 0;
 }
 
-char *get_task_name(pid_t pid)
+int get_task_name(pid_t pid, char *name)
 {
-	char *comm;
+	char path[PATH_MAX];
 	FILE *f;
 
 	if (!pid)
-		return NULL;
+		return -1;
 
-	if (asprintf(&comm, "/proc/%d/comm", pid) < 0)
-		return NULL;
+	if (snprintf(path, sizeof(path), "/proc/%d/comm", pid) >= sizeof(path))
+		return -1;
 
-	f = fopen(comm, "r");
+	f = fopen(path, "r");
 	if (!f)
-		return NULL;
+		return -1;
 
-	if (fscanf(f, "%ms\n", &comm) != 1)
-		comm = NULL;
+	if (fscanf(f, "%s\n", name) != 1)
+		return -1;
 
 	fclose(f);
 
-	return comm;
+	return 0;
 }
rdma/res-cmid.c +5 -3
index bfaa47b5..3475349d 100644
@@ -159,8 +159,11 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -199,8 +202,7 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-cq.c +5 -3
index 9e7c4f51..5ed455ea 100644
@@ -84,8 +84,11 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -123,8 +126,7 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-ctx.c +4 -3
index 30afe97a..fbd52dd5 100644
@@ -18,8 +18,11 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
 		return MNL_CB_ERROR;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -48,8 +51,6 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-mr.c +4 -3
index 1bf73f3a..6a59d9e4 100644
@@ -47,8 +47,11 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -87,8 +90,6 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-pd.c +5 -3
index df538010..a51bb634 100644
@@ -34,8 +34,11 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
 			nla_line[RDMA_NLDEV_ATTR_RES_UNSAFE_GLOBAL_RKEY]);
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -76,8 +79,7 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-qp.c +4 -3
index a38be399..575e0529 100644
@@ -146,8 +146,11 @@ static int res_qp_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -179,8 +182,6 @@ static int res_qp_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-srq.c +4 -3
index 3038c352..945109fc 100644
@@ -174,8 +174,11 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
 		return MNL_CB_ERROR;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 	if (rd_is_filtered_attr(rd, "pid", pid,
 				nla_line[RDMA_NLDEV_ATTR_RES_PID]))

@@ -228,8 +231,6 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/stat.c +4 -1
index adfcd34a..a63b70a4 100644
@@ -248,8 +248,11 @@ static int res_counter_line(struct rd *rd, const char *name, int index,
 		return MNL_CB_OK;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 	if (rd_is_filtered_attr(rd, "pid", pid,
 				nla_line[RDMA_NLDEV_ATTR_RES_PID]))
Signature · 1 line
2.35.1
#6 lore raw

Re: [PATCH iproute2 v2 1/2] lib/fs: fix memory leak in get_task_name()

In reply to Andrea Claudi

include/utils.h char *find_cgroup2_mount(bool do_mount); · line 311

Quoted 11 lines · Andrea Claudi
include/utils.h +1 -1
index b6c468e9..81294488 100644
@@ -307,7 +307,7 @@ char *find_cgroup2_mount(bool do_mount);
 __u64 get_cgroup2_id(const char *path);
 char *get_cgroup2_path(__u64 id, bool full);
 int get_command_name(const char *pid, char *comm, size_t len);
-char *get_task_name(pid_t pid);
+int get_task_name(pid_t pid, char *name);

changing to an API with an assumed length is not better than the current situation. Why not just fixup the callers as needed to free the allocation?

author
#3 lore raw

Re: [PATCH iproute2 v2 1/2] lib/fs: fix memory leak in get_task_name()

In reply to Leon Romanovsky

Hi Leon,
Thanks for your review.

Quoted 7 lines · Leon Romanovsky
Quoted 2 lines · Andrea Claudi

asprintf() allocates memory which is not freed on the error path of get_task_name(), thus potentially leading to memory leaks.

Not really, memory is released when the application exits, which is the case here.

That's certainly true. However this is still a leak in the time frame between get_task_name function call and the application exit. For example:

$ ip -d -b - << EOF
tuntap show
monitor
EOF

calls get_task_name one or more time (once for each tun interface), and leaks memory indefinitely, if ip is not interrupted in some way.

Of course this is a corner case, and the leaks should anyway be small. However I cannot see this as a good reason not to fix it.

Quoted 9 lines
Quoted 6 lines

Rework get_task_name() and avoid asprintf() usage and memory allocation, returning the task string to the caller using an additional char* parameter.

Fixes 81bfd01a4c9e ("lib: move get_task_name() from rdma")

As I was told before, in netdev Fixes means that it is a bug that affects users. This is not the case here.

Thanks for letting me know. I usually rely a lot on Fixes: as iproute2 package maintainer, but I'll change my habits if this is the common understanding. Stephen, David, WDYT?

Quoted 309 lines
Quoted 15 lines
Signed-off-by Andrea Claudi <[email protected]>
---
 include/utils.h |  2 +-
 ip/iptuntap.c   | 17 ++++++++++-------
 lib/fs.c        | 20 ++++++++++----------
 rdma/res-cmid.c |  8 +++++---
 rdma/res-cq.c   |  8 +++++---
 rdma/res-ctx.c  |  7 ++++---
 rdma/res-mr.c   |  7 ++++---
 rdma/res-pd.c   |  8 +++++---
 rdma/res-qp.c   |  7 ++++---
 rdma/res-srq.c  |  7 ++++---
 rdma/stat.c     |  5 ++++-
 11 files changed, 56 insertions(+), 40 deletions(-)

Honestly, I don't see any need in both patches.

Thanks

Quoted 288 lines
include/utils.h +1 -1
index b6c468e9..81294488 100644
@@ -307,7 +307,7 @@ char *find_cgroup2_mount(bool do_mount);
 __u64 get_cgroup2_id(const char *path);
 char *get_cgroup2_path(__u64 id, bool full);
 int get_command_name(const char *pid, char *comm, size_t len);
-char *get_task_name(pid_t pid);
+int get_task_name(pid_t pid, char *name);
 
 int get_rtnl_link_stats_rta(struct rtnl_link_stats64 *stats64,
 			    struct rtattr *tb[]);
ip/iptuntap.c +10 -7
index 385d2bd8..2ae6b1a1 100644
@@ -321,14 +321,17 @@ static void show_processes(const char *name)
 			} else if (err == 2 &&
 				   !strcmp("iff", key) &&
 				   !strcmp(name, value)) {
-				char *pname = get_task_name(pid);
-
-				print_string(PRINT_ANY, "name",
-					     "%s", pname ? : "<NULL>");
+				SPRINT_BUF(pname);
+
+				if (get_task_name(pid, pname)) {
+					print_string(PRINT_ANY, "name",
+						     "%s", "<NULL>");
+				} else {
+					print_string(PRINT_ANY, "name",
+						     "%s", pname);
+				}
 
-				print_uint(PRINT_ANY, "pid",
-					   "(%d)", pid);
-				free(pname);
+				print_uint(PRINT_ANY, "pid", "(%d)", pid);
 			}
 
 			free(key);
lib/fs.c +10 -10
index f6f5f8a0..03df0f6a 100644
@@ -342,25 +342,25 @@ int get_command_name(const char *pid, char *comm, size_t len)
 	return 0;
 }
 
-char *get_task_name(pid_t pid)
+int get_task_name(pid_t pid, char *name)
 {
-	char *comm;
+	char path[PATH_MAX];
 	FILE *f;
 
 	if (!pid)
-		return NULL;
+		return -1;
 
-	if (asprintf(&comm, "/proc/%d/comm", pid) < 0)
-		return NULL;
+	if (snprintf(path, sizeof(path), "/proc/%d/comm", pid) >= sizeof(path))
+		return -1;
 
-	f = fopen(comm, "r");
+	f = fopen(path, "r");
 	if (!f)
-		return NULL;
+		return -1;
 
-	if (fscanf(f, "%ms\n", &comm) != 1)
-		comm = NULL;
+	if (fscanf(f, "%s\n", name) != 1)
+		return -1;
 
 	fclose(f);
 
-	return comm;
+	return 0;
 }
rdma/res-cmid.c +5 -3
index bfaa47b5..3475349d 100644
@@ -159,8 +159,11 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -199,8 +202,7 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-cq.c +5 -3
index 9e7c4f51..5ed455ea 100644
@@ -84,8 +84,11 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -123,8 +126,7 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-ctx.c +4 -3
index 30afe97a..fbd52dd5 100644
@@ -18,8 +18,11 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
 		return MNL_CB_ERROR;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -48,8 +51,6 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-mr.c +4 -3
index 1bf73f3a..6a59d9e4 100644
@@ -47,8 +47,11 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -87,8 +90,6 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-pd.c +5 -3
index df538010..a51bb634 100644
@@ -34,8 +34,11 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
 			nla_line[RDMA_NLDEV_ATTR_RES_UNSAFE_GLOBAL_RKEY]);
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -76,8 +79,7 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-qp.c +4 -3
index a38be399..575e0529 100644
@@ -146,8 +146,11 @@ static int res_qp_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -179,8 +182,6 @@ static int res_qp_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-srq.c +4 -3
index 3038c352..945109fc 100644
@@ -174,8 +174,11 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
 		return MNL_CB_ERROR;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 	if (rd_is_filtered_attr(rd, "pid", pid,
 				nla_line[RDMA_NLDEV_ATTR_RES_PID]))

@@ -228,8 +231,6 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/stat.c +4 -1
index adfcd34a..a63b70a4 100644
@@ -248,8 +248,11 @@ static int res_counter_line(struct rd *rd, const char *name, int index,
 		return MNL_CB_OK;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 	if (rd_is_filtered_attr(rd, "pid", pid,
 				nla_line[RDMA_NLDEV_ATTR_RES_PID]))
Signature · 1 line
2.35.1
#4 lore raw

Re: [PATCH iproute2 v2 1/2] lib/fs: fix memory leak in get_task_name()

Quoted 3 lines · Andrea Claudi

Thanks for letting me know. I usually rely a lot on Fixes: as iproute2 package maintainer, but I'll change my habits if this is the common understanding. Stephen, David, WDYT?

I think a Fixes tag is relevant here.

#7 lore raw

Re: [PATCH iproute2 v2 1/2] lib/fs: fix memory leak in get_task_name()

In reply to David Ahern
Quoted 15 lines · On Mon, 7 Mar 2022 10:58:37 -0700 David Ahern <[email protected]> wrote:

include/utils.h char *find_cgroup2_mount(bool do_mount); · line 311

Quoted 11 lines · Andrea Claudi
include/utils.h +1 -1
index b6c468e9..81294488 100644
@@ -307,7 +307,7 @@ char *find_cgroup2_mount(bool do_mount);
 __u64 get_cgroup2_id(const char *path);
 char *get_cgroup2_path(__u64 id, bool full);
 int get_command_name(const char *pid, char *comm, size_t len);
-char *get_task_name(pid_t pid);
+int get_task_name(pid_t pid, char *name);

changing to an API with an assumed length is not better than the current situation. Why not just fixup the callers as needed to free the allocation?

I wonder if iproute2 should start using GCC attribute cleanup function (like systemd) or would this be too much of using a new thing?

Not sure if using the attribute (wrapped in macro) just hides the problem

author
#8 lore raw

Re: [PATCH iproute2 v2 1/2] lib/fs: fix memory leak in get_task_name()

In reply to David Ahern
Quoted 16 lines · David Ahern

include/utils.h char *find_cgroup2_mount(bool do_mount); · line 311

Quoted 11 lines · Andrea Claudi
include/utils.h +1 -1
index b6c468e9..81294488 100644
@@ -307,7 +307,7 @@ char *find_cgroup2_mount(bool do_mount);
 __u64 get_cgroup2_id(const char *path);
 char *get_cgroup2_path(__u64 id, bool full);
 int get_command_name(const char *pid, char *comm, size_t len);
-char *get_task_name(pid_t pid);
+int get_task_name(pid_t pid, char *name);

changing to an API with an assumed length is not better than the current situation. Why not just fixup the callers as needed to free the allocation?

I actually did that on v1. After Stephen's comment about asprintf(), I got the idea to make get_task_name() similar to get_command_name() and a bit more "user-friendly", so that callers do not need a free().

If you think this is not ideal, I can post a v3 with the necessary fixes to the callers.

Thanks,
Andrea

#9 lore raw

Re: [PATCH iproute2 v2 1/2] lib/fs: fix memory leak in get_task_name()

Quoted 22 lines · On Mon, 7 Mar 2022 19:21:41 +0100 Andrea Claudi <[email protected]> wrote:
Quoted 16 lines · David Ahern

include/utils.h char *find_cgroup2_mount(bool do_mount); · line 311

Quoted 11 lines · Andrea Claudi
include/utils.h +1 -1
index b6c468e9..81294488 100644
@@ -307,7 +307,7 @@ char *find_cgroup2_mount(bool do_mount);
 __u64 get_cgroup2_id(const char *path);
 char *get_cgroup2_path(__u64 id, bool full);
 int get_command_name(const char *pid, char *comm, size_t len);
-char *get_task_name(pid_t pid);
+int get_task_name(pid_t pid, char *name);

changing to an API with an assumed length is not better than the current situation. Why not just fixup the callers as needed to free the allocation?

I actually did that on v1. After Stephen's comment about asprintf(), I got the idea to make get_task_name() similar to get_command_name() and a bit more "user-friendly", so that callers do not need a free().

Quoted 6 lines

If you think this is not ideal, I can post a v3 with the necessary fixes to the callers.

Thanks,
Andrea

My comment was purely a suggestion not a requirement.
I have just had issues with complaints from compiler about code not checking return value from asprintf, so tend to avoid it.

#10 lore raw

Re: [PATCH iproute2 v2 1/2] lib/fs: fix memory leak in get_task_name()

In reply to Andrea Claudi
Quoted 18 lines · Andrea Claudi
Quoted 16 lines · David Ahern

include/utils.h char *find_cgroup2_mount(bool do_mount); · line 311

Quoted 11 lines · Andrea Claudi
include/utils.h +1 -1
index b6c468e9..81294488 100644
@@ -307,7 +307,7 @@ char *find_cgroup2_mount(bool do_mount);
 __u64 get_cgroup2_id(const char *path);
 char *get_cgroup2_path(__u64 id, bool full);
 int get_command_name(const char *pid, char *comm, size_t len);
-char *get_task_name(pid_t pid);
+int get_task_name(pid_t pid, char *name);

changing to an API with an assumed length is not better than the current situation. Why not just fixup the callers as needed to free the allocation?

Quoted 4 lines

I actually did that on v1. After Stephen's comment about asprintf(), I got the idea to make get_task_name() similar to get_command_name() and a bit more "user-friendly", so that callers do not need a free().

get_command_name passes a buffer and length. That's a better API - no assumptions.

#5 lore raw

Re: [PATCH iproute2 v2 1/2] lib/fs: fix memory leak in get_task_name()

In reply to Andrea Claudi
Quoted 32 lines · Andrea Claudi

Hi Leon,
Thanks for your review.

Quoted 7 lines · Leon Romanovsky
Quoted 2 lines · Andrea Claudi

asprintf() allocates memory which is not freed on the error path of get_task_name(), thus potentially leading to memory leaks.

Not really, memory is released when the application exits, which is the case here.

That's certainly true. However this is still a leak in the time frame between get_task_name function call and the application exit. For example:

$ ip -d -b - << EOF
tuntap show
monitor
EOF

calls get_task_name one or more time (once for each tun interface), and leaks memory indefinitely, if ip is not interrupted in some way.

Of course this is a corner case, and the leaks should anyway be small. However I cannot see this as a good reason not to fix it.

Quoted 5 lines
Quoted 5 lines

Rework get_task_name() and avoid asprintf() usage and memory allocation, returning the task string to the caller using an additional char* parameter.

Quoted 14 lines
Quoted 4 lines
Quoted 1 line
Fixes 81bfd01a4c9e ("lib: move get_task_name() from rdma")

As I was told before, in netdev Fixes means that it is a bug that affects users. This is not the case here.

Thanks for letting me know. I usually rely a lot on Fixes: as iproute2 package maintainer, but I'll change my habits if this is the common understanding. Stephen, David, WDYT?

Quoted 5 lines
Quoted 5 lines
Signed-off-by Andrea Claudi <[email protected]>
---
 include/utils.h |  2 +-
 ip/iptuntap.c   | 17 ++++++++++-------

Ahh, sorry, I missed this user.
So yes, Fixes is needed here.

Thanks

Quoted 305 lines
Quoted 304 lines
Quoted 10 lines
 lib/fs.c        | 20 ++++++++++----------
 rdma/res-cmid.c |  8 +++++---
 rdma/res-cq.c   |  8 +++++---
 rdma/res-ctx.c  |  7 ++++---
 rdma/res-mr.c   |  7 ++++---
 rdma/res-pd.c   |  8 +++++---
 rdma/res-qp.c   |  7 ++++---
 rdma/res-srq.c  |  7 ++++---
 rdma/stat.c     |  5 ++++-
 11 files changed, 56 insertions(+), 40 deletions(-)

Honestly, I don't see any need in both patches.

Thanks

Quoted 288 lines
include/utils.h +1 -1
index b6c468e9..81294488 100644
@@ -307,7 +307,7 @@ char *find_cgroup2_mount(bool do_mount);
 __u64 get_cgroup2_id(const char *path);
 char *get_cgroup2_path(__u64 id, bool full);
 int get_command_name(const char *pid, char *comm, size_t len);
-char *get_task_name(pid_t pid);
+int get_task_name(pid_t pid, char *name);
 
 int get_rtnl_link_stats_rta(struct rtnl_link_stats64 *stats64,
 			    struct rtattr *tb[]);
ip/iptuntap.c +10 -7
index 385d2bd8..2ae6b1a1 100644
@@ -321,14 +321,17 @@ static void show_processes(const char *name)
 			} else if (err == 2 &&
 				   !strcmp("iff", key) &&
 				   !strcmp(name, value)) {
-				char *pname = get_task_name(pid);
-
-				print_string(PRINT_ANY, "name",
-					     "%s", pname ? : "<NULL>");
+				SPRINT_BUF(pname);
+
+				if (get_task_name(pid, pname)) {
+					print_string(PRINT_ANY, "name",
+						     "%s", "<NULL>");
+				} else {
+					print_string(PRINT_ANY, "name",
+						     "%s", pname);
+				}
 
-				print_uint(PRINT_ANY, "pid",
-					   "(%d)", pid);
-				free(pname);
+				print_uint(PRINT_ANY, "pid", "(%d)", pid);
 			}
 
 			free(key);
lib/fs.c +10 -10
index f6f5f8a0..03df0f6a 100644
@@ -342,25 +342,25 @@ int get_command_name(const char *pid, char *comm, size_t len)
 	return 0;
 }
 
-char *get_task_name(pid_t pid)
+int get_task_name(pid_t pid, char *name)
 {
-	char *comm;
+	char path[PATH_MAX];
 	FILE *f;
 
 	if (!pid)
-		return NULL;
+		return -1;
 
-	if (asprintf(&comm, "/proc/%d/comm", pid) < 0)
-		return NULL;
+	if (snprintf(path, sizeof(path), "/proc/%d/comm", pid) >= sizeof(path))
+		return -1;
 
-	f = fopen(comm, "r");
+	f = fopen(path, "r");
 	if (!f)
-		return NULL;
+		return -1;
 
-	if (fscanf(f, "%ms\n", &comm) != 1)
-		comm = NULL;
+	if (fscanf(f, "%s\n", name) != 1)
+		return -1;
 
 	fclose(f);
 
-	return comm;
+	return 0;
 }
rdma/res-cmid.c +5 -3
index bfaa47b5..3475349d 100644
@@ -159,8 +159,11 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -199,8 +202,7 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-cq.c +5 -3
index 9e7c4f51..5ed455ea 100644
@@ -84,8 +84,11 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -123,8 +126,7 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-ctx.c +4 -3
index 30afe97a..fbd52dd5 100644
@@ -18,8 +18,11 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
 		return MNL_CB_ERROR;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -48,8 +51,6 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-mr.c +4 -3
index 1bf73f3a..6a59d9e4 100644
@@ -47,8 +47,11 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -87,8 +90,6 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-pd.c +5 -3
index df538010..a51bb634 100644
@@ -34,8 +34,11 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
 			nla_line[RDMA_NLDEV_ATTR_RES_UNSAFE_GLOBAL_RKEY]);
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -76,8 +79,7 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 
-out:	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
+out:
 	return MNL_CB_OK;
 }
rdma/res-qp.c +4 -3
index a38be399..575e0529 100644
@@ -146,8 +146,11 @@ static int res_qp_line(struct rd *rd, const char *name, int idx,
 		goto out;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 
 	if (rd_is_filtered_attr(rd, "pid", pid,

@@ -179,8 +182,6 @@ static int res_qp_line(struct rd *rd, const char *name, int idx,
 	print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
 	newline(rd);
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/res-srq.c +4 -3
index 3038c352..945109fc 100644
@@ -174,8 +174,11 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
 		return MNL_CB_ERROR;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 	if (rd_is_filtered_attr(rd, "pid", pid,
 				nla_line[RDMA_NLDEV_ATTR_RES_PID]))

@@ -228,8 +231,6 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
 	newline(rd);
 
 out:
-	if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
-		free(comm);
 	return MNL_CB_OK;
 }
rdma/stat.c +4 -1
index adfcd34a..a63b70a4 100644
@@ -248,8 +248,11 @@ static int res_counter_line(struct rd *rd, const char *name, int index,
 		return MNL_CB_OK;
 
 	if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
+		SPRINT_BUF(b);
+
 		pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
-		comm = get_task_name(pid);
+		if (!get_task_name(pid, b))
+			comm = b;
 	}
 	if (rd_is_filtered_attr(rd, "pid", pid,
 				nla_line[RDMA_NLDEV_ATTR_RES_PID]))
Signature · 1 line
2.35.1