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 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: 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 6642accc628a..97a1fa140a9b 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3696,13 +3696,14 @@ 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);