Messages in this thread | | | Date | Thu, 13 Jun 2013 16:20:28 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 1/2] hw_breakpoint: Fix cpu check in task_bp_pinned(cpu) |
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On Sat, Jun 01, 2013 at 08:21:20PM +0200, Oleg Nesterov wrote: > 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> > Cc: <stable@vger.kernel.org>
Looks good, thanks!
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
> --- > kernel/events/hw_breakpoint.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c > index ed1c897..29d3abe 100644 > --- a/kernel/events/hw_breakpoint.c > +++ b/kernel/events/hw_breakpoint.c > @@ -120,7 +120,7 @@ static int task_bp_pinned(int cpu, struct perf_event *bp, enum bp_type_idx type) > 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); > } > > -- > 1.5.5.1 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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