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authorEric Dumazet <edumazet@google.com>2017-03-03 21:01:02 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-03-22 12:04:15 +0100
commit9e7683301beef0cef8254eecb661e7eac3146717 (patch)
tree77ca5ec4803bd38846630fb5484486e6597ca792 /net
parent2681a7853ad73bfebc3a683765a496bb283c6648 (diff)
net: fix socket refcounting in skb_complete_wifi_ack()
[ 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-rw-r--r--net/core/skbuff.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4968b5ddea69..370f4f86e2b5 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3735,7 +3735,7 @@ 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;
@@ -3745,14 +3745,15 @@ 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);