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authorEric Dumazet <edumazet@google.com>2017-03-04 08:01:03 +0300
committerDavid S. Miller <davem@davemloft.net>2017-03-08 01:06:15 +0300
commit9ac25fc063751379cb77434fef9f3b088cd3e2f7 (patch)
tree411965f359568a7dfd8c23d68fbb0d68e43c356e /net
parentdd4f10722aeb10f4f582948839f066bebe44e5fb (diff)
downloadlinux-9ac25fc063751379cb77434fef9f3b088cd3e2f7.tar.xz
net: fix socket refcounting in skb_complete_tx_timestamp()
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 and lead to leaks or use after free. Fixes: 62bccb8cdb69 ("net-timestamp: Make the clone operation stand-alone from phy timestamping") 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>
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 e2f37a560ec4..cd4ba8c6b609 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3828,13 +3828,14 @@ void skb_complete_tx_timestamp(struct sk_buff *skb,
if (!skb_may_tx_timestamp(sk, false))
return;
- /* take a reference to prevent skb_orphan() from freeing the socket */
- sock_hold(sk);
-
- *skb_hwtstamps(skb) = *hwtstamps;
- __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);
-
- sock_put(sk);
+ /* 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))) {
+ *skb_hwtstamps(skb) = *hwtstamps;
+ __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);
+ sock_put(sk);
+ }
}
EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);