[PATCH 4.3 012/125] net: avoid NULL deref in inet_ctl_sock_destroy()

[Greg Kroah-Hartman]

4.3-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit 8fa677d2706d325d71dab91bf6e6512c05214e37 ]

Under low memory conditions, tcp_sk_init() and icmp_sk_init()
can both iterate on all possible cpus and call inet_ctl_sock_destroy(),
with eventual NULL pointer.

Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 include/net/inet_common.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/include/net/inet_common.h
+++ b/include/net/inet_common.h
@@ -41,7 +41,8 @@ int inet_recv_error(struct sock *sk, str
 
 static inline void inet_ctl_sock_destroy(struct sock *sk)
 {
-	sock_release(sk->sk_socket);
+	if (sk)
+		sock_release(sk->sk_socket);
 }
 
 #endif


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