From: Kan Liang Date: Fri, 12 Mar 2021 13:21:38 +0000 (-0800) Subject: perf/x86/intel: Fix unchecked MSR access error caused by VLBR_EVENT X-Git-Tag: v5.11.9~21 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=ec872a2c1c5466c95085ba1ba4df1a4ff91dc246;p=thirdparty%2Fkernel%2Fstable.git perf/x86/intel: Fix unchecked MSR access error caused by VLBR_EVENT commit 2dc0572f2cef87425147658698dce2600b799bd3 upstream. On a Haswell machine, the perf_fuzzer managed to trigger this message: [117248.075892] unchecked MSR access error: WRMSR to 0x3f1 (tried to write 0x0400000000000000) at rIP: 0xffffffff8106e4f4 (native_write_msr+0x4/0x20) [117248.089957] Call Trace: [117248.092685] intel_pmu_pebs_enable_all+0x31/0x40 [117248.097737] intel_pmu_enable_all+0xa/0x10 [117248.102210] __perf_event_task_sched_in+0x2df/0x2f0 [117248.107511] finish_task_switch.isra.0+0x15f/0x280 [117248.112765] schedule_tail+0xc/0x40 [117248.116562] ret_from_fork+0x8/0x30 A fake event called VLBR_EVENT may use the bit 58 of the PEBS_ENABLE, if the precise_ip is set. The bit 58 is reserved by the HW. Accessing the bit causes the unchecked MSR access error. The fake event doesn't support PEBS. The case should be rejected. Fixes: 097e4311cda9 ("perf/x86: Add constraint to create guest LBR event without hw counter") Reported-by: Vince Weaver Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1615555298-140216-2-git-send-email-kan.liang@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index d3f5cf70c1a09..bfd42e0853ed6 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3575,6 +3575,9 @@ static int intel_pmu_hw_config(struct perf_event *event) return ret; if (event->attr.precise_ip) { + if ((event->attr.config & INTEL_ARCH_EVENT_MASK) == INTEL_FIXED_VLBR_EVENT) + return -EINVAL; + if (!(event->attr.freq || (event->attr.wakeup_events && !event->attr.watermark))) { event->hw.flags |= PERF_X86_EVENT_AUTO_RELOAD; if (!(event->attr.sample_type &