llc: Fix race condition in llc_ui_recvmsg
There is a race on sk_receive_queue between llc_ui_recvmsg and
sock_queue_rcv_skb.
Our current solution is to protect skb_eat in llc_ui_recvmsg
with the queue spinlock.
Signed-off-by: Radu Iliescu <riliescu@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index a18e6c3..b9bef2c 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -713,6 +713,7 @@
struct sk_buff *skb = NULL;
struct sock *sk = sock->sk;
struct llc_sock *llc = llc_sk(sk);
+ unsigned long cpu_flags;
size_t copied = 0;
u32 peek_seq = 0;
u32 *seq;
@@ -838,7 +839,9 @@
goto copy_uaddr;
if (!(flags & MSG_PEEK)) {
+ spin_lock_irqsave(&sk->sk_receive_queue.lock, cpu_flags);
sk_eat_skb(sk, skb, 0);
+ spin_unlock_irqrestore(&sk->sk_receive_queue.lock, cpu_flags);
*seq = 0;
}
@@ -859,7 +862,9 @@
llc_cmsg_rcv(msg, skb);
if (!(flags & MSG_PEEK)) {
+ spin_lock_irqsave(&sk->sk_receive_queue.lock, cpu_flags);
sk_eat_skb(sk, skb, 0);
+ spin_unlock_irqrestore(&sk->sk_receive_queue.lock, cpu_flags);
*seq = 0;
}