perf: Limit perf_event_attr::sample_period to 63 bits
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@maine.edu> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/n/tip-p25fhunibl4y3qi0zuqmyf4b@git.kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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@ -7029,6 +7029,9 @@ SYSCALL_DEFINE5(perf_event_open,
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if (attr.freq) {
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if (attr.freq) {
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if (attr.sample_freq > sysctl_perf_event_sample_rate)
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if (attr.sample_freq > sysctl_perf_event_sample_rate)
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return -EINVAL;
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return -EINVAL;
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} else {
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if (attr.sample_period & (1ULL << 63))
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return -EINVAL;
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}
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}
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/*
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/*
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