sh, hw_breakpoints: Fix racy access to ptrace breakpoints
authorFrederic Weisbecker <fweisbec@gmail.com>
Fri, 8 Apr 2011 15:29:36 +0000 (17:29 +0200)
committerFrederic Weisbecker <fweisbec@gmail.com>
Mon, 25 Apr 2011 15:36:12 +0000 (17:36 +0200)
commite0ac8457d020c0289ea566917267da9e5e6d9865
tree85c7ad75fc186feceffac2de16b5a195d0cae8af
parentbf0b8f4b55e591ba417c2dbaff42769e1fc773b0
sh, hw_breakpoints: Fix racy access to ptrace breakpoints

While the tracer accesses ptrace breakpoints, the child task may
concurrently exit due to a SIGKILL and thus release its breakpoints
at the same time. We can then dereference some freed pointers.

To fix this, hold a reference on the child breakpoints before
manipulating them.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1302284067-7860-6-git-send-email-fweisbec@gmail.com
arch/sh/kernel/ptrace_32.c