TX skbs do not necessarily hold a reference on skb->sk->sk_refcnt
By the time TX completion happens, sk_refcnt might be already 0.
sock_hold()/sock_put() would then corrupt critical state, like
sk_wmem_alloc.
Fixes: bf7fa551e0ce ("mac80211: Resolve sk_refcnt/sk_wmem_alloc issue in wifi
ack path")
Signed-off-by: Eric Dumazet <[email protected]>
Cc: Alexander Duyck <[email protected]>
Cc: Johannes Berg <[email protected]>
Cc: Soheil Hassas Yeganeh <[email protected]>
Cc: Willem de Bruijn <[email protected]>
---
net/core/skbuff.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index
f3557958e9bf147631a90b51fef0630920acd97b..e2f37a560ec43ccf60a71f190423bd265eccf594
100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3893,7 +3893,7 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool
acked)
{
struct sock *sk = skb->sk;
struct sock_exterr_skb *serr;
- int err;
+ int err = 1;
skb->wifi_acked_valid = 1;
skb->wifi_acked = acked;
@@ -3903,14 +3903,15 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool
acked)
serr->ee.ee_errno = ENOMSG;
serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
- /* take a reference to prevent skb_orphan() from freeing the socket */
- sock_hold(sk);
-
- err = sock_queue_err_skb(sk, skb);
+ /* Take a reference to prevent skb_orphan() from freeing the socket,
+ * but only if the socket refcount is not zero.
+ */
+ if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) {
+ err = sock_queue_err_skb(sk, skb);
+ sock_put(sk);
+ }
if (err)
kfree_skb(skb);
-
- sock_put(sk);
}
EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
--
2.12.0.rc1.440.g5b76565f74-goog
