From: Eric Dumazet edumazet@google.com
This patch has been added to the stable tree. If you have any objections, please let us know.
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[ Upstream commit dd4f10722aeb10f4f582948839f066bebe44e5fb ]
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 edumazet@google.com Cc: Alexander Duyck alexander.h.duyck@intel.com Cc: Johannes Berg johannes@sipsolutions.net Cc: Soheil Hassas Yeganeh soheil@google.com Cc: Willem de Bruijn willemb@google.com Acked-by: Soheil Hassas Yeganeh soheil@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- 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 2894bb5b7e0a..6642accc628a 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3753,7 +3753,7 @@ 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; @@ -3763,14 +3763,15 @@ 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);