Messages in this thread | | | Date | Fri, 07 Oct 2011 16:06:45 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH 07/12] perf_events: add LBR software filter support for Intel X86 |
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(2011/10/07 1:43), Peter Zijlstra wrote: > On Thu, 2011-10-06 at 17:32 +0200, Andi Kleen wrote: >>> + kernel_insn_init(&insn, kaddr); >>> + insn_get_opcode(&insn); >> >> This makes me uncomfortable. AFAIK that's the first use of the opcode >> decoder being used directly for user space. It has a quite large attack >> surface. Who says it cannot be exploited? > > You mean: > arch/x86/kernel/cpu/perf_event_intel_ds.c:intel_pmu_pebs_fixup_ip() > doesn't use the opcode decoder on user space code? > > ISTR Masami telling me they ran fuzzers on it, feeding it bad > instructions etc. But maybe he can tell more.
I've tested it by decoding userspace libraries and binaries. It is also easy to test decoding with random binaries too :) I'll try to do that.
Thanks,
-- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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