From 293ad60401da621b8b329abbe8c388edb25f658a Mon Sep 17 00:00:00 2001 From: Octavian Purdila Date: Wed, 4 Jun 2008 15:45:58 -0700 Subject: tcp: Fix for race due to temporary drop of the socket lock in skb_splice_bits. skb_splice_bits temporary drops the socket lock while iterating over the socket queue in order to break a reverse locking condition which happens with sendfile. This, however, opens a window of opportunity for tcp_collapse() to aggregate skbs and thus potentially free the current skb used in skb_splice_bits and tcp_read_sock. This patch fixes the problem by (re-)getting the same "logical skb" after the lock has been temporary dropped. Based on idea and initial patch from Evgeniy Polyakov. Signed-off-by: Octavian Purdila Acked-by: Evgeniy Polyakov Signed-off-by: David S. Miller --- net/core/skbuff.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'net/core/skbuff.c') diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 5c459f2b7985..1e556d312117 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1445,6 +1445,7 @@ done: if (spd.nr_pages) { int ret; + struct sock *sk = __skb->sk; /* * Drop the socket lock, otherwise we have reverse @@ -1455,9 +1456,9 @@ done: * we call into ->sendpage() with the i_mutex lock held * and networking will grab the socket lock. */ - release_sock(__skb->sk); + release_sock(sk); ret = splice_to_pipe(pipe, &spd); - lock_sock(__skb->sk); + lock_sock(sk); return ret; } -- cgit v1.2.3