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authorEric Dumazet <edumazet@google.com>2017-03-03 21:01:03 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-03-22 12:43:33 +0100
commitf157cc1d7251403c950d960e3bcf988c14d9deda (patch)
tree42f7d5d8756c2490181c6179282b1c965a2a7473 /net/core/skbuff.c
parent98fa3d2a8e399c40f681bca83f8ab522657c16db (diff)
net: fix socket refcounting in skb_complete_tx_timestamp()
[ Upstream commit 9ac25fc063751379cb77434fef9f3b088cd3e2f7 ] 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/core/skbuff.c')
-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 b806677f9fd3..f0f462c0573d 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3814,13 +3814,14 @@ 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);