Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 06/26] hw_breakpoint: Fix cpu check in task_bp_pinned(cpu) | Date | Mon, 1 Jul 2013 13:10:01 -0700 |
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3.9-stable review patch. If anyone has any objections, please let me know.
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From: Oleg Nesterov <oleg@redhat.com>
commit 8b4d801b2b123b6c09742f861fe44a8527b84d47 upstream.
trinity fuzzer triggered WARN_ONCE("Can't find any breakpoint slot") in arch_install_hw_breakpoint() but the problem is not arch-specific.
The problem is, task_bp_pinned(cpu) checks "cpu == iter->cpu" but this doesn't account the "all cpus" events with iter->cpu < 0.
This means that, say, register_user_hw_breakpoint(tsk) can happily create the arbitrary number > HBP_NUM of breakpoints which can not be activated. toggle_bp_task_slot() is equally wrong by the same reason and nr_task_bp_pinned[] can have negative entries.
Simple test:
# perl -e 'sleep 1 while 1' & # perf record -e mem:0x10,mem:0x10,mem:0x10,mem:0x10,mem:0x10 -p `pidof perl`
Before this patch this triggers the same problem/WARN_ON(), after the patch it correctly fails with -ENOSPC.
Reported-by: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20130620155006.GA6324@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/events/hw_breakpoint.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -120,7 +120,7 @@ static int task_bp_pinned(int cpu, struc list_for_each_entry(iter, &bp_task_head, hw.bp_list) { if (iter->hw.bp_target == tsk && find_slot_idx(iter) == type && - cpu == iter->cpu) + (iter->cpu < 0 || cpu == iter->cpu)) count += hw_breakpoint_weight(iter); }
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