From: Paul Mackerras Date: Tue, 15 Dec 2009 08:40:32 +0000 (+1100) Subject: perf_event: Fix incorrect range check on cpu number X-Git-Tag: v2.6.32.2~2 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=517361c51d4a762531e669ebb2c081a1e678455a;p=karo-tx-linux.git perf_event: Fix incorrect range check on cpu number 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 Signed-off-by: Paul Mackerras Tested-by: Michael Neuling Acked-by: Peter Zijlstra LKML-Reference: <20091215084032.GA18661@brick.ozlabs.ibm.com> Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 61c35f583b90..6eee915a939e 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -1583,7 +1583,7 @@ static struct perf_event_context *find_get_context(pid_t pid, int cpu) 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); /*