From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 8 May 2014 11:47:49 +0000 (-0400)
Subject: tracepoint: Fix use of tracepoint funcs after rcu free
X-Git-Tag: omap-for-v3.16/fixes-against-rc1~200^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8058bd0faad860e75547cc5cb5d4ade016247a79;p=pandora-kernel.git

tracepoint: Fix use of tracepoint funcs after rcu free

Commit de7b2973903c "tracepoint: Use struct pointer instead of name hash
for reg/unreg tracepoints" introduces a use after free by calling
release_probes on the old struct tracepoint array before the newly
allocated array is published with rcu_assign_pointer. There is a race
window where tracepoints (RCU readers) can perform a
"use-after-grace-period-after-free", which shows up as a GPF in
stress-tests.

Link: http://lkml.kernel.org/r/53698021.5020108@oracle.com
Link: http://lkml.kernel.org/p/1399549669-25465-1-git-send-email-mathieu.desnoyers@efficios.com

Reported-by: Sasha Levin <sasha.levin@oracle.com>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Dave Jones <davej@redhat.com>
Fixes: de7b2973903c "tracepoint: Use struct pointer instead of name hash for reg/unreg tracepoints"
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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