Commit 878b5a6e authored Sep 11, 2013 by Oleg Nesterov Committed by Ingo Molnar Sep 12, 2013

uprobes: Fix utask->depth accounting in handle_trampoline()



Currently utask->depth is simply the number of allocated/pending
return_instance's in uprobe_task->return_instances list.

handle_trampoline() should decrement this counter every time we
handle/free an instance, but due to typo it does this only if
->chained == T. This means that in the likely case this counter
is never decremented and the probed task can't report more than
MAX_URETPROBE_DEPTH events.

Reported-by: Mikhail Kulemin <Mikhail.Kulemin@ru.ibm.com>
Reported-by: Hemant Kumar Shaw <hkshaw@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Cc: masami.hiramatsu.pt@hitachi.com
Cc: srikar@linux.vnet.ibm.com
Cc: systemtap@sourceware.org
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20130911154726.GA8093@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 6113af14

kernel/events/uprobes.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -1682,12 +1682,10 @@ static bool handle_trampoline(struct pt_regs *regs)
		tmp = ri;
		ri = ri->next;
		kfree(tmp);
		utask->depth--;

		if (!chained)
		break;

		utask->depth--;

		BUG_ON(!ri);
		}

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