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Date: Sat, 07 Jun 2014 02:26:29 +0100 From: Ben Hutchings <ben@...adent.org.uk> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org CC: akpm@...ux-foundation.org, "Thomas Gleixner" <tglx@...utronix.de>, "Vince Weaver" <vincent.weaver@...ne.edu>, "Peter Zijlstra" <peterz@...radead.org> Subject: [PATCH 3.2 76/92] perf: Limit perf_event_attr::sample_period to 63 bits 3.2.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra <peterz@...radead.org> commit 0819b2e30ccb93edf04876237b6205eef84ec8d2 upstream. Vince reported that using a large sample_period (one with bit 63 set) results in wreckage since while the sample_period is fundamentally unsigned (negative periods don't make sense) the way we implement things very much rely on signed logic. So limit sample_period to 63 bits to avoid tripping over this. Reported-by: Vince Weaver <vincent.weaver@...ne.edu> Signed-off-by: Peter Zijlstra <peterz@...radead.org> Link: http://lkml.kernel.org/n/tip-p25fhunibl4y3qi0zuqmyf4b@git.kernel.org Signed-off-by: Thomas Gleixner <tglx@...utronix.de> Signed-off-by: Ben Hutchings <ben@...adent.org.uk> --- kernel/events/core.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6301,6 +6301,9 @@ SYSCALL_DEFINE5(perf_event_open, if (attr.freq) { if (attr.sample_freq > sysctl_perf_event_sample_rate) return -EINVAL; + } else { + if (attr.sample_period & (1ULL << 63)) + return -EINVAL; } /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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