This is a note to let you know that I've just added the patch titled
perf/x86/intel/lbr: Fix LBR filter
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-x86-intel-lbr-fix-lbr-filter.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 6e15eb3ba6c0249c9e8c783517d131b47db995ca Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <[email protected]>
Date: Fri, 3 May 2013 14:11:24 +0200
Subject: perf/x86/intel/lbr: Fix LBR filter
From: Peter Zijlstra <[email protected]>
commit 6e15eb3ba6c0249c9e8c783517d131b47db995ca 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 <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/kernel/cpu/perf_event_intel_lbr.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -442,8 +442,18 @@ static int branch_type(unsigned long fro
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
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/perf-x86-intel-lbr-demand-proper-privileges-for-perf_sample_branch_kernel.patch
queue-3.4/perf-x86-intel-lbr-fix-lbr-filter.patch
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