Commit 88d4f0db authored Jan 25, 2011 by Eric Dumazet Committed by Ingo Molnar Jan 27, 2011

perf: Fix alloc_callchain_buffers()



Commit 927c7a9e ("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>

parent 6fb1b304

kernel/perf_event.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -1999,8 +1999,7 @@ static int alloc_callchain_buffers(void)
		* accessed from NMI. Use a temporary manual per cpu allocation
		* until that gets sorted out.
		*/
		size = sizeof(entries) + sizeof(struct perf_callchain_entry ) *
		num_possible_cpus();
		size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);

		entries = kzalloc(size, GFP_KERNEL);
		if (!entries)