[ 071/167] [PATCH 11/26] net: fix a race in sock_queue_err_skb()

Ben Hutchings
2012-05-09T06:22:58Z

From: Eric Dumazet <eric.dumazet@gmail.com>

[ Upstream commit 110c43304db6f06490961529536c362d9ac5732f ]

As soon as an skb is queued into socket error queue, another thread
can consume it, so we are not allowed to reference skb anymore, or risk
use after free.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/core/skbuff.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 3c30ee4..29cb392 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3111,6 +3111,8 @@ static void sock_rmem_free(struct sk_buff *skb)
*/
int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
{
+ int len = skb->len;
+
if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
(unsigned)sk->sk_rcvbuf)
return -ENOMEM;
@@ -3125,7 +3127,7 @@ int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)

skb_queue_tail(&sk->sk_error_queue, skb);
if (!sock_flag(sk, SOCK_DEAD))
- sk->sk_data_ready(sk, skb->len);
+ sk->sk_data_ready(sk, len);
return 0;
}
EXPORT_SYMBOL(sock_queue_err_skb);
--
1.7.10