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authorFrederic Weisbecker <fweisbec@gmail.com>2011-04-08 17:29:36 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2011-04-25 17:36:12 +0200
commite0ac8457d020c0289ea566917267da9e5e6d9865 (patch)
tree85c7ad75fc186feceffac2de16b5a195d0cae8af /arch/sh
parentbf0b8f4b55e591ba417c2dbaff42769e1fc773b0 (diff)
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
Diffstat (limited to 'arch/sh')
-rw-r--r--arch/sh/kernel/ptrace_32.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c
index 2130ca674e9b..3d7b209b2178 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)