Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 5/5] sh, hw_breakpoints: Fix racy access to ptrace breakpoints | Date | Tue, 3 May 2011 15:25:24 +0200 |
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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 --- arch/sh/kernel/ptrace_32.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c index 2130ca6..3d7b209 100644 --- a/arch/sh/kernel/ptrace_32.c +++ b/arch/sh/kernel/ptrace_32.c @@ -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) -- 1.7.3.2
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