Messages in this thread |  | | | From | Sonny Rao <> | | Date | Mon, 18 Apr 2011 14:02:52 -0700 | | Subject | Re: [PATCH] Fix infinite loop in ARM user perf_event backtrace code |
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On Mon, Apr 18, 2011 at 10:42 AM, Will Deacon <will.deacon@arm.com> wrote: > Hi Sonny, > > On Sat, 2011-04-16 at 04:27 +0100, Sonny Rao wrote: >> The ARM user backtrace code can get into an infinite loop if it >> runs into an invalid stack frame which points back to itself. >> This situation has been observed in practice. Fix it by capping >> the number of entries in the backtrace. This is also what other >> architectures do in their backtrace code. >> >> Signed-off-by: Sonny Rao <sonnyrao@chromium.org> >> --- >> arch/arm/kernel/perf_event.c | 3 ++- >> 1 files changed, 2 insertions(+), 1 deletions(-) >> >> diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c >> index 69cfee0..1e61d60 100644 >> --- a/arch/arm/kernel/perf_event.c >> +++ b/arch/arm/kernel/perf_event.c >> @@ -746,7 +746,8 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) >> >> tail = (struct frame_tail __user *)regs->ARM_fp - 1; >> >> - while (tail && !((unsigned long)tail & 0x3)) >> + while ((entry->nr < PERF_MAX_STACK_DEPTH) && >> + tail && !((unsigned long)tail & 0x3)) >> tail = user_backtrace(tail, entry); >> } > > Ok. Please can you put this into Russell's patch system? > > Will >
Ok, sent it to patches@arm.linux.org.uk hope that'll be sufficient -- 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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