From 0f624e7e5625f4c30c836b7a5decfe2553582391 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Tue, 15 Dec 2009 19:40:32 +1100 Subject: [PATCH] perf_event: Fix incorrect range check on cpu number 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 Cc: LKML-Reference: <20091215084032.GA18661@brick.ozlabs.ibm.com> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index d891ec4a8100..8823b0885183 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -1603,7 +1603,7 @@ 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); /* -- 2.30.2