Commit e0ac8457 authored by Frederic Weisbecker's avatar Frederic Weisbecker

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: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarPaul 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
parent bf0b8f4b
...@@ -117,7 +117,11 @@ void user_enable_single_step(struct task_struct *child) ...@@ -117,7 +117,11 @@ void user_enable_single_step(struct task_struct *child)
set_tsk_thread_flag(child, TIF_SINGLESTEP); set_tsk_thread_flag(child, TIF_SINGLESTEP);
if (ptrace_get_breakpoints(child) < 0)
return;
set_single_step(child, pc); set_single_step(child, pc);
ptrace_put_breakpoints(child);
} }
void user_disable_single_step(struct task_struct *child) void user_disable_single_step(struct task_struct *child)
......
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