Thomas Gleixner d2753e6b48 perf/x86/amd/ibs: Don't access non-started event ... Paul Menzel reported the following bug: > Enabling the undefined behavior sanitizer and building GNU/Linux 4.18-rc5+ > (with some unrelated commits) with GCC 8.1.0 from Debian Sid/unstable, the > warning below is shown. > > > [ 2.111913] > > ================================================================================ > > [ 2.111917] UBSAN: Undefined behaviour in arch/x86/events/amd/ibs.c:582:24 > > [ 2.111919] member access within null pointer of type 'struct perf_event' > > [ 2.111926] CPU: 0 PID: 144 Comm: udevadm Not tainted 4.18.0-rc5-00316-g4864b68cedf2 #104 > > [ 2.111928] Hardware name: ASROCK E350M1/E350M1, BIOS TIMELESS 01/01/1970 > > [ 2.111930] Call Trace: > > [ 2.111943] dump_stack+0x55/0x89 > > [ 2.111949] ubsan_epilogue+0xb/0x33 > > [ 2.111953] handle_null_ptr_deref+0x7f/0x90 > > [ 2.111958] __ubsan_handle_type_mismatch_v1+0x55/0x60 > > [ 2.111964] perf_ibs_handle_irq+0x596/0x620 The code dereferences event before checking the STARTED bit. Patch below should cure the issue. The warning should not trigger, if I analyzed the thing correctly. (And Paul's testing confirms this.) Reported-by: Paul Menzel <pmenzel@molgen.mpg.de> Tested-by: Paul Menzel <pmenzel@molgen.mpg.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Menzel <pmenzel+linux-x86@molgen.mpg.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Vince Weaver <vincent.weaver@maine.edu> Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1807200958390.1580@nanos.tec.linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>		2018-07-24 09:51:10 +02:00
..
core.c	x86/events: Remove last remnants of old filenames	2017-03-01 11:27:26 +01:00
ibs.c	perf/x86/amd/ibs: Don't access non-started event	2018-07-24 09:51:10 +02:00
iommu.c	treewide: kzalloc() -> kcalloc()	2018-06-12 16:19:22 -07:00
iommu.h	x86/events, drivers/amd/iommu: Prepare for multiple IOMMUs support	2017-03-30 09:53:55 +02:00
Makefile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
power.c	perf/x86/amd/power: Do not load AMD power module on !AMD platforms	2018-01-24 13:00:35 +01:00
uncore.c	perf/events/amd/uncore: Fix amd_uncore_llc ID to use pre-defined cpu_llc_id	2018-05-06 12:49:15 +02:00