| Date | Wed, 16 Dec 2009 19:57:27 -0800 | From | Greg KH <> | Subject | [150/151] perf_event: Fix incorrect range check on cpu number |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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From: Paul Mackerras <paulus@samba.org>
commit 0f624e7e5625f4c30c836b7a5decfe2553582391 upstream.
It is quite legitimate for CPUs to be numbered sparsely, meaning that it possible for an online CPU to have a number which is greater than the total count of possible CPUs.
Currently find_get_context() has a sanity check on the cpu number where it checks it against num_possible_cpus(). This test can fail for a legitimate cpu number if the cpu_possible_mask is sparsely populated.
This fixes the problem by checking the CPU number against nr_cpumask_bits instead, since that is the appropriate check to ensure that the cpu number is same to pass to cpu_isset() subsequently.
Reported-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Paul Mackerras <paulus@samba.org> Tested-by: Michael Neuling <mikey@neuling.org> Acked-by: Peter Zijlstra <peterz@infradead.org> LKML-Reference: <20091215084032.GA18661@brick.ozlabs.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- kernel/perf_event.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -1583,7 +1583,7 @@ static struct perf_event_context *find_g if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN)) return ERR_PTR(-EACCES); - if (cpu < 0 || cpu > num_possible_cpus()) + if (cpu < 0 || cpu >= nr_cpumask_bits) return ERR_PTR(-EINVAL); /*
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