diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2013-05-03 14:11:24 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-05-11 07:18:21 -0700 |
| commit | d851a41c72181e5170a3a81fa124c678bd449a1c (patch) | |
| tree | e4bd48ff5564e296ba27d5a9a33db0fc730804b5 | |
| parent | 1a2d6c494667deb43c5dfca27b719a1446a1d641 (diff) | |
| download | lwn-d851a41c72181e5170a3a81fa124c678bd449a1c.tar.gz lwn-d851a41c72181e5170a3a81fa124c678bd449a1c.zip | |
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event_intel_lbr.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index da02e9cc3754..de341d4ec92a 100644 --- 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 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 |