Tools: hv: Fix for long file names from readdir

PATCH In review Tomas Hozza 3 participants 6 messages Nov 8, 2012 – Nov 26, 2012 Hyper-V/Azure core and drivers

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Tomas Hozza

author

2012-11-08 14:13 UTC #0 lore raw

PATCH 1/1 Tools: hv: Fix for long file names from readdir

kvp_get_if_name and kvp_mac_to_if_name copy strings into statically sized buffers which could be too small to store really long names.

Buffer sizes have been increased and length checks added via snprintf.

Signed-off-by Tomas Hozza <[email protected]>

---
 tools/hv/hv_kvp_daemon.c | 25 ++++++++-----------------
 1 file changed, 8 insertions(+), 17 deletions(-)

tools/hv/hv_kvp_daemon.c +8 ~~-17~~

index 13c2a14..bbd426c 100644
@@ -592,26 +592,22 @@ static char *kvp_get_if_name(char *guid)
 	DIR *dir;
 	struct dirent *entry;
 	FILE    *file;
-	char    *p, *q, *x;
+	char    *p, *x;
 	char    *if_name = NULL;
 	char    buf[256];
 	char *kvp_net_dir = "/sys/class/net/";
-	char dev_id[256];
+	char dev_id[512];
 
 	dir = opendir(kvp_net_dir);
 	if (dir == NULL)
 		return NULL;
 
-	snprintf(dev_id, sizeof(dev_id), "%s", kvp_net_dir);
-	q = dev_id + strlen(kvp_net_dir);
-
 	while ((entry = readdir(dir)) != NULL) {
 		/*
 		 * Set the state for the next pass.
 		 */
-		*q = '\0';
-		strcat(dev_id, entry->d_name);
-		strcat(dev_id, "/device/device_id");
+		snprintf(dev_id, sizeof(dev_id), "%s%s/device/device_id", kvp_net_dir,
+				entry->d_name);
 
 		file = fopen(dev_id, "r");
 		if (file == NULL)

@@ -684,28 +680,23 @@ static char *kvp_mac_to_if_name(char *mac)
 	DIR *dir;
 	struct dirent *entry;
 	FILE    *file;
-	char    *p, *q, *x;
+	char    *p, *x;
 	char    *if_name = NULL;
 	char    buf[256];
 	char *kvp_net_dir = "/sys/class/net/";
-	char dev_id[256];
+	char dev_id[512];
 	int i;
 
 	dir = opendir(kvp_net_dir);
 	if (dir == NULL)
 		return NULL;
 
-	snprintf(dev_id, sizeof(dev_id), kvp_net_dir);
-	q = dev_id + strlen(kvp_net_dir);
-
 	while ((entry = readdir(dir)) != NULL) {
 		/*
 		 * Set the state for the next pass.
 		 */
-		*q = '\0';
-
-		strcat(dev_id, entry->d_name);
-		strcat(dev_id, "/address");
+		snprintf(dev_id, sizeof(dev_id), "%s%s/address", kvp_net_dir,
+                entry->d_name);
 
 		file = fopen(dev_id, "r");
 		if (file == NULL)

Signature · 1 line

1.7.11.7

Olaf Hering

2012-11-08 14:34 UTC #1 lore raw

Review

Quoted 5 lines · Tomas Hozza

kvp_get_if_name and kvp_mac_to_if_name copy strings into statically sized buffers which could be too small to store really long names.
(quoted diff) +1 -1
-	char dev_id[256];
+	char dev_id[512];

Shouldnt that be PATH_MAX or similar?

Olaf

Tomas Hozza

author

2012-11-08 14:52 UTC #2 lore raw

Quoted 4 lines

Review
Quoted 2 lines
(quoted diff) +1 -1
-        char dev_id[256];
+        char dev_id[512];
Shouldnt that be PATH_MAX or similar?

dirent->d_name should be PATH_MAX, but it is mostly not guaranteed. And then the dev_id is concatenated with two strings so it can exceed 256 bytes.

After discussion with K. Y. Srinivasan I just doubled the size and added size checks for sanity.

Tomas

KY Srinivasan

2012-11-08 15:59 UTC #3 lore raw

Quoted 11 lines

-----Original Message-----
From: Tomas Hozza [mailto:[email protected]]
Sent: Thursday, November 08, 2012 9:53 AM
To: Olaf Hering
Cc: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; KY Srinivasan
Subject: Re: [PATCH] Tools: hv: Fix for long file names from readdir

Quoted 8 lines

Quoted 4 lines
Review
Quoted 2 lines
(quoted diff) +1 -1
-        char dev_id[256];
+        char dev_id[512];
Shouldnt that be PATH_MAX or similar?
dirent->d_name should be PATH_MAX, but it is mostly not guaranteed. And then the dev_id is concatenated with two strings so it can exceed 256 bytes.

PATH_MAX (currently 4096 bytes) I think should suffice.

Regards,

K. Y

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Tomas Hozza

author

2012-11-09 12:48 UTC #4 lore raw

PATCH 1/1 Tools: hv: Fix for long file names from readdir

kvp_get_if_name and kvp_mac_to_if_name copy strings into statically sized buffers which could be too small to store really long names.

Buffer sizes have been changed to PATH_MAX, include "limits.h" where PATH_MAX is defined was added and length checks ware added via snprintf.

Signed-off-by Tomas Hozza <[email protected]>

---
 tools/hv/hv_kvp_daemon.c | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

tools/hv/hv_kvp_daemon.c +9 ~~-17~~

index 13c2a14..54ecb95 100644
@@ -44,6 +44,7 @@
 #include <fcntl.h>
 #include <dirent.h>
 #include <net/if.h>
+#include <limits.h>
 
 /*
  * KVP protocol: The user mode component first registers with the

@@ -592,26 +593,22 @@ static char *kvp_get_if_name(char *guid)
 	DIR *dir;
 	struct dirent *entry;
 	FILE    *file;
-	char    *p, *q, *x;
+	char    *p, *x;
 	char    *if_name = NULL;
 	char    buf[256];
 	char *kvp_net_dir = "/sys/class/net/";
-	char dev_id[256];
+	char dev_id[PATH_MAX];
 
 	dir = opendir(kvp_net_dir);
 	if (dir == NULL)
 		return NULL;
 
-	snprintf(dev_id, sizeof(dev_id), "%s", kvp_net_dir);
-	q = dev_id + strlen(kvp_net_dir);
-
 	while ((entry = readdir(dir)) != NULL) {
 		/*
 		 * Set the state for the next pass.
 		 */
-		*q = '\0';
-		strcat(dev_id, entry->d_name);
-		strcat(dev_id, "/device/device_id");
+		snprintf(dev_id, sizeof(dev_id), "%s%s/device/device_id", kvp_net_dir,
+				entry->d_name);
 
 		file = fopen(dev_id, "r");
 		if (file == NULL)

@@ -684,28 +681,23 @@ static char *kvp_mac_to_if_name(char *mac)
 	DIR *dir;
 	struct dirent *entry;
 	FILE    *file;
-	char    *p, *q, *x;
+	char    *p, *x;
 	char    *if_name = NULL;
 	char    buf[256];
 	char *kvp_net_dir = "/sys/class/net/";
-	char dev_id[256];
+	char dev_id[PATH_MAX];
 	int i;
 
 	dir = opendir(kvp_net_dir);
 	if (dir == NULL)
 		return NULL;
 
-	snprintf(dev_id, sizeof(dev_id), kvp_net_dir);
-	q = dev_id + strlen(kvp_net_dir);
-
 	while ((entry = readdir(dir)) != NULL) {
 		/*
 		 * Set the state for the next pass.
 		 */
-		*q = '\0';
-
-		strcat(dev_id, entry->d_name);
-		strcat(dev_id, "/address");
+		snprintf(dev_id, sizeof(dev_id), "%s%s/address", kvp_net_dir,
+                entry->d_name);
 
 		file = fopen(dev_id, "r");
 		if (file == NULL)

Signature · 1 line

1.7.11.7

KY Srinivasan

Acked-by on v1 1/1

2012-11-26 20:44 UTC #5 lore raw

Quoted 11 lines

-----Original Message-----
From: Tomas Hozza [mailto:[email protected]]
Sent: Friday, November 09, 2012 7:47 AM
To: [email protected]; KY Srinivasan
Cc: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Tomas Hozza
Subject: [PATCH] Tools: hv: Fix for long file names from readdir

Quoted 7 lines

kvp_get_if_name and kvp_mac_to_if_name copy strings into statically sized buffers which could be too small to store really long names.
Buffer sizes have been changed to PATH_MAX, include "limits.h" where PATH_MAX is defined was added and length checks ware added via snprintf.
Signed-off-by Tomas Hozza <[email protected]>

Acked-by K. Y. Srinivasan <[email protected]>

Quoted 83 lines

---
 tools/hv/hv_kvp_daemon.c | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

tools/hv/hv_kvp_daemon.c +5 -8

index 13c2a14..54ecb95 100644
@@ -44,6 +44,7 @@
 #include <fcntl.h>
 #include <dirent.h>
 #include <net/if.h>
+#include <limits.h>
 
 /*
  * KVP protocol: The user mode component first registers with the

@@ -592,26 +593,22 @@ static char *kvp_get_if_name(char *guid)
 	DIR *dir;
 	struct dirent *entry;
 	FILE    *file;
-	char    *p, *q, *x;
+	char    *p, *x;
 	char    *if_name = NULL;
 	char    buf[256];
 	char *kvp_net_dir = "/sys/class/net/";
-	char dev_id[256];
+	char dev_id[PATH_MAX];
 
 	dir = opendir(kvp_net_dir);
 	if (dir == NULL)
 		return NULL;
 
-	snprintf(dev_id, sizeof(dev_id), "%s", kvp_net_dir);
-	q = dev_id + strlen(kvp_net_dir);
-
 	while ((entry = readdir(dir)) != NULL) {
 		/*
 		 * Set the state for the next pass.
 		 */
-		*q = '\0';
-		strcat(dev_id, entry->d_name);
-		strcat(dev_id, "/device/device_id");
+		snprintf(dev_id, sizeof(dev_id), "%s%s/device/device_id",
 kvp_net_dir,
+				entry->d_name);
 
 		file = fopen(dev_id, "r");

tools/hv/hv_kvp_daemon.c +4 ~~-10~~

 		if (file == NULL)

@@ -684,28 +681,23 @@ static char *kvp_mac_to_if_name(char *mac)
 	DIR *dir;
 	struct dirent *entry;
 	FILE    *file;
-	char    *p, *q, *x;
+	char    *p, *x;
 	char    *if_name = NULL;
 	char    buf[256];
 	char *kvp_net_dir = "/sys/class/net/";
-	char dev_id[256];
+	char dev_id[PATH_MAX];
 	int i;
 
 	dir = opendir(kvp_net_dir);
 	if (dir == NULL)
 		return NULL;
 
-	snprintf(dev_id, sizeof(dev_id), kvp_net_dir);
-	q = dev_id + strlen(kvp_net_dir);
-
 	while ((entry = readdir(dir)) != NULL) {
 		/*
 		 * Set the state for the next pass.
 		 */
-		*q = '\0';
-
-		strcat(dev_id, entry->d_name);
-		strcat(dev_id, "/address");
+		snprintf(dev_id, sizeof(dev_id), "%s%s/address", kvp_net_dir,
+                entry->d_name);
 
 		file = fopen(dev_id, "r");
 		if (file == NULL)
--

1.7.11.7