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authorVegard Nossum <vegard.nossum@gmail.com>2008-09-11 19:05:29 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2008-10-08 19:44:44 -0700
commit8d9f9fdc074522b022abfa500a25a072d5e13113 (patch)
tree1dea23c6b616ef396808a825a61c210a94ae8500
parente808212e98c4d8032c7bf88a0f122d58daff6621 (diff)
netlink: fix overrun in attribute iteration
[ Upstream commit 1045b03e07d85f3545118510a587035536030c1c ] kmemcheck reported this: kmemcheck: Caught 16-bit read from uninitialized memory (f6c1ba30) 0500110001508abf050010000500000002017300140000006f72672e66726565 i i i i i i i i i i i i i u u u u u u u u u u u u u u u u u u u ^ Pid: 3462, comm: wpa_supplicant Not tainted (2.6.27-rc3-00054-g6397ab9-dirty #13) EIP: 0060:[<c05de64a>] EFLAGS: 00010296 CPU: 0 EIP is at nla_parse+0x5a/0xf0 EAX: 00000008 EBX: fffffffd ECX: c06f16c0 EDX: 00000005 ESI: 00000010 EDI: f6c1ba30 EBP: f6367c6c ESP: c0a11e88 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 CR0: 8005003b CR2: f781cc84 CR3: 3632f000 CR4: 000006d0 DR0: c0ead9bc DR1: 00000000 DR2: 00000000 DR3: 00000000 DR6: ffff4ff0 DR7: 00000400 [<c05d4b23>] rtnl_setlink+0x63/0x130 [<c05d5f75>] rtnetlink_rcv_msg+0x165/0x200 [<c05ddf66>] netlink_rcv_skb+0x76/0xa0 [<c05d5dfe>] rtnetlink_rcv+0x1e/0x30 [<c05dda21>] netlink_unicast+0x281/0x290 [<c05ddbe9>] netlink_sendmsg+0x1b9/0x2b0 [<c05beef2>] sock_sendmsg+0xd2/0x100 [<c05bf945>] sys_sendto+0xa5/0xd0 [<c05bf9a6>] sys_send+0x36/0x40 [<c05c03d6>] sys_socketcall+0x1e6/0x2c0 [<c020353b>] sysenter_do_call+0x12/0x3f [<ffffffff>] 0xffffffff This is the line in nla_ok(): /** * nla_ok - check if the netlink attribute fits into the remaining bytes * @nla: netlink attribute * @remaining: number of bytes remaining in attribute stream */ static inline int nla_ok(const struct nlattr *nla, int remaining) { return remaining >= sizeof(*nla) && nla->nla_len >= sizeof(*nla) && nla->nla_len <= remaining; } It turns out that remaining can become negative due to alignment in nla_next(). But GCC promotes "remaining" to unsigned in the test against sizeof(*nla) above. Therefore the test succeeds, and the nla_for_each_attr() may access memory outside the received buffer. A short example illustrating this point is here: #include <stdio.h> main(void) { printf("%d\n", -1 >= sizeof(int)); } ...which prints "1". This patch adds a cast in front of the sizeof so that GCC will make a signed comparison and fix the illegal memory dereference. With the patch applied, there is no kmemcheck report. Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--include/net/netlink.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/net/netlink.h b/include/net/netlink.h
index 112dcdf7e34e..5383fdffd0db 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -704,7 +704,7 @@ static inline int nla_len(const struct nlattr *nla)
*/
static inline int nla_ok(const struct nlattr *nla, int remaining)
{
- return remaining >= sizeof(*nla) &&
+ return remaining >= (int) sizeof(*nla) &&
nla->nla_len >= sizeof(*nla) &&
nla->nla_len <= remaining;
}