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perf/x86/intel/lbr: Fix LBR filter

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commit 6e15eb3ba6 upstream.

The LBR 'from' adddress is under full userspace control; ensure
we validate it before reading from it.

Note: is_module_text_address() can potentially be quite
expensive; for those running into that with high overhead
in modules optimize it using an RCU backed rb-tree.

Reported-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/20130503121256.158211806@chello.nl
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/n/tip-mk8i82ffzax01cnqo829iy1q@git.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Zijlstra 2013-05-03 14:11:24 +02:00 committed by Greg Kroah-Hartman
parent e233f3f5c5
commit 59be003dc4
1 changed files with 12 additions and 2 deletions
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14
arch/x86/kernel/cpu/perf_event_intel_lbr.c
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@ -442,8 +442,18 @@ static int branch_type(unsigned long from, unsigned long to)
return X86_BR_NONE;
addr = buf;
} else
addr = (void *)from;
} else {
/*
* The LBR logs any address in the IP, even if the IP just
* faulted. This means userspace can control the from address.
* Ensure we don't blindy read any address by validating it is
* a known text address.
*/
if (kernel_text_address(from))
addr = (void *)from;
else
return X86_BR_NONE;
}
/*
* decoder needs to know the ABI especially