3.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Peter Zijlstra <a.p.zijls...@chello.nl> 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 <a...@linux.intel.com> Signed-off-by: Peter Zijlstra <a.p.zijls...@chello.nl> Cc: eran...@google.com Link: http://lkml.kernel.org/r/20130503121256.158211...@chello.nl Signed-off-by: Ingo Molnar <mi...@kernel.org> Link: http://lkml.kernel.org/n/tip-mk8i82ffzax01cnqo829i...@git.kernel.org Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
