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net: ipv4: current group_info should be put after using.

PATCH In review Wang, Xiaoming 2 participants 3 messages Apr 11, 2014

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Wang, Xiaoming

author
#0 lore raw

PATCH 1/1 net: ipv4: current group_info should be put after using.

There is a memory leak in ping. Current group_info had been got in ping_init_sock and group_info->usage increased.
But the usage hasn't decreased anywhere in ping.
This will make this group_info never freed and cause memory leak.

unreferenced object 0xcd0e8840 (size 192):
comm "dumpstate", pid 7583, jiffies 78360 (age 91.810s) hex dump (first 32 bytes):

    02 00 00 00 06 00 00 00 01 00 00 00 ef 03 00 00  ................
    f1 03 00 00 f7 03 00 00 04 04 00 00 bb 0b 00 00  ................
  backtrace:
    [<c1a6bbfc>] kmemleak_alloc+0x3c/0xa0
    [<c1320457>] __kmalloc+0xe7/0x1d0
    [<c1267c04>] groups_alloc+0x34/0xb0
    [<c1267e5c>] SyS_setgroups+0x3c/0xf0
    [<c1a864a8>] syscall_call+0x7/0xb
    [<ffffffff>] 0xffffffff
Signed-off-by Chuansheng Liu <[email protected]>
Signed-off-by Zhang Dongxing <[email protected]>
Signed-off-by xiaoming wang <[email protected]>
---
 net/ipv4/ping.c |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)
net/ipv4/ping.c +8 -3
index f4b19e5..2af7b1f 100644
@@ -255,23 +255,28 @@ int ping_init_sock(struct sock *sk)
 	struct group_info *group_info = get_current_groups();
 	int i, j, count = group_info->ngroups;
 	kgid_t low, high;
+	int ret = 0;
 
 	inet_get_ping_group_range_net(net, &low, &high);
 	if (gid_lte(low, group) && gid_lte(group, high))
-		return 0;
+		goto out_release_group;
 
 	for (i = 0; i < group_info->nblocks; i++) {
 		int cp_count = min_t(int, NGROUPS_PER_BLOCK, count);
 		for (j = 0; j < cp_count; j++) {
 			kgid_t gid = group_info->blocks[i][j];
 			if (gid_lte(low, gid) && gid_lte(gid, high))
-				return 0;
+				goto out_release_group;
 		}
 
 		count -= cp_count;
 	}
 
-	return -EACCES;
+	ret = -EACCES;
+
+out_release_group:
+	put_group_info(group_info);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(ping_init_sock);
Signature · 1 line
1.7.1
#1 lore raw
Quoted 5 lines · Xiaoming

There is a memory leak in ping. Current group_info had been got in ping_init_sock and group_info->usage increased.
But the usage hasn't decreased anywhere in ping.
This will make this group_info never freed and cause memory leak.

Memory leak is only one of possible side-effects, thus I believe commit message should be adjusted.

This is a typical refcount leak exploitable by unprivileged users, so side effects can range from nothing through memory leaks and crashes to possibly privilege escalation.

That said losing ' and cause memory leak' from your commit message would be fine in my opinion.

See also a nit below.

Quoted 9 lines
---
 net/ipv4/ping.c |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)
net/ipv4/ping.c +0 -0
index f4b19e5..2af7b1f 100644

net/ipv4/ping.c int ping_init_sock(struct sock *sk) · line 263

Quoted 10 lines
net/ipv4/ping.c +2 -1
@@ -255,23 +255,28 @@ int ping_init_sock(struct sock *sk)
 	struct group_info *group_info = get_current_groups();
 	int i, j, count = group_info->ngroups;
 	kgid_t low, high;
+	int ret = 0;
 
 	inet_get_ping_group_range_net(net, &low, &high);
 	if (gid_lte(low, group) && gid_lte(group, high))
-		return 0;
+		goto out_release_group;

Since group_info is not even used here maybe it would be better to leave return 0 as it is and call get_current_groups before the loop?

Quoted 21 lines
net/ipv4/ping.c +6 -2
 	for (i = 0; i < group_info->nblocks; i++) {
 		int cp_count = min_t(int, NGROUPS_PER_BLOCK, count);
 		for (j = 0; j < cp_count; j++) {
 			kgid_t gid = group_info->blocks[i][j];
 			if (gid_lte(low, gid) && gid_lte(gid, high))
-				return 0;
+				goto out_release_group;
 		}
 
 		count -= cp_count;
 	}
 
-	return -EACCES;
+	ret = -EACCES;
+
+out_release_group:
+	put_group_info(group_info);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(ping_init_sock);
Signature · 1 line
Mateusz Guzik
#2 lore raw
Quoted 10 lines · Mateusz Guzik
Quoted 5 lines · Xiaoming

There is a memory leak in ping. Current group_info had been got in ping_init_sock and group_info->usage increased.
But the usage hasn't decreased anywhere in ping.
This will make this group_info never freed and cause memory leak.

Memory leak is only one of possible side-effects, thus I believe commit message should be adjusted.

Quoted 7 lines

This is a typical refcount leak exploitable by unprivileged users, so side effects can range from nothing through memory leaks and crashes to possibly privilege escalation.

That said losing ' and cause memory leak' from your commit message would be fine in my opinion.

Huh, not sure why I wrote that last sentence, it does not make much sense. Sorry.

There is a pending CVE request for this bug:
http://seclists.org/oss-sec/2014/q2/97

The bug was introduced with:
commit c319b4d76b9e583a5d88d6bf190e079c4e43213d

Author: Vasiliy Kulikov <[email protected]>
Date:   Fri May 13 10:01:00 2011 +0000

net: ipv4: add IPPROTO_ICMP socket kind

starting with 3.0 kernel.

Quoted 49 lines

See also a nit below.

Quoted 9 lines
---
 net/ipv4/ping.c |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)
net/ipv4/ping.c +0 -0
index f4b19e5..2af7b1f 100644

net/ipv4/ping.c int ping_init_sock(struct sock *sk) · line 263

Quoted 10 lines
net/ipv4/ping.c +2 -1
@@ -255,23 +255,28 @@ int ping_init_sock(struct sock *sk)
 	struct group_info *group_info = get_current_groups();
 	int i, j, count = group_info->ngroups;
 	kgid_t low, high;
+	int ret = 0;
 
 	inet_get_ping_group_range_net(net, &low, &high);
 	if (gid_lte(low, group) && gid_lte(group, high))
-		return 0;
+		goto out_release_group;

Since group_info is not even used here maybe it would be better to leave return 0 as it is and call get_current_groups before the loop?

Quoted 21 lines
net/ipv4/ping.c +6 -2
 	for (i = 0; i < group_info->nblocks; i++) {
 		int cp_count = min_t(int, NGROUPS_PER_BLOCK, count);
 		for (j = 0; j < cp_count; j++) {
 			kgid_t gid = group_info->blocks[i][j];
 			if (gid_lte(low, gid) && gid_lte(gid, high))
-				return 0;
+				goto out_release_group;
 		}
 
 		count -= cp_count;
 	}
 
-	return -EACCES;
+	ret = -EACCES;
+
+out_release_group:
+	put_group_info(group_info);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(ping_init_sock);
Signature · 1 line
Mateusz Guzik
Signature · 1 line
Mateusz Guzik