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sh, hw_breakpoints: Fix racy access to ptrace breakpoints

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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
This commit is contained in:
Frederic Weisbecker 2011-04-08 17:29:36 +02:00
parent bf0b8f4b55
commit e0ac8457d0
1 changed files with 4 additions and 0 deletions
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4
arch/sh/kernel/ptrace_32.c
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@ -117,7 +117,11 @@ void user_enable_single_step(struct task_struct *child)
set_tsk_thread_flag(child, TIF_SINGLESTEP);
if (ptrace_get_breakpoints(child) < 0)
return;
set_single_step(child, pc);
ptrace_put_breakpoints(child);
}
void user_disable_single_step(struct task_struct *child)