@@ -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
This is a note to let you know that I have just added a patch titled perf/x86/intel/lbr: Fix LBR filter to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 0a0482e443ce13cf68b7b3f40eac34d5b2a3546c Mon Sep 17 00:00:00 2001 From: Peter Zijlstra <a.p.zijlstra@chello.nl> Date: Fri, 3 May 2013 14:11:24 +0200 Subject: [PATCH] perf/x86/intel/lbr: Fix LBR filter 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 <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: Luis Henriques <luis.henriques@canonical.com> --- arch/x86/kernel/cpu/perf_event_intel_lbr.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) -- 1.8.1.2