From: Octavian Purdila <opurdila@ixiacom.com>
Date: Wed, 4 Jun 2008 22:45:58 +0000 (-0700)
Subject: tcp: Fix for race due to temporary drop of the socket lock in skb_splice_bits.
X-Git-Tag: v2.6.26-rc5~1^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=293ad60401da621b8b329abbe8c388edb25f658a;p=pandora-kernel.git

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 <opurdila@ixiacom.com>
Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
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