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perf: Fix alloc_callchain_buffers()

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Commit 927c7a9e92 ("perf: Fix race in callchains") introduced
a mismatch in the sizing of struct callchain_cpus_entries.

nr_cpu_ids must be used instead of num_possible_cpus(), or we
might get out of bound memory accesses on some machines.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Miller <davem@davemloft.net>
Cc: Stephane Eranian <eranian@google.com>
CC: stable@kernel.org
LKML-Reference: <1295980851.3588.351.camel@edumazet-laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Eric Dumazet
2011-01-25 19:40:51 +01:00
committed by Ingo Molnar
parent 6fb1b30425
commit 88d4f0db7f
1 changed files with 1 additions and 2 deletions
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3
kernel/perf_event.c
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@@ -1999,8 +1999,7 @@ static int alloc_callchain_buffers(void)
* accessed from NMI. Use a temporary manual per cpu allocation * accessed from NMI. Use a temporary manual per cpu allocation
* until that gets sorted out. * until that gets sorted out.
*/ */
size = sizeof(*entries) + sizeof(struct perf_callchain_entry *) * size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);
num_possible_cpus();
entries = kzalloc(size, GFP_KERNEL); entries = kzalloc(size, GFP_KERNEL);
if (!entries) if (!entries)