linux/arch/x86/events
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
..
amd perf/x86/amd/ibs: Don't access non-started event 2018-07-24 09:51:10 +02:00
intel x86/events/intel/ds: Fix bts_interrupt_threshold alignment 2018-07-15 11:38:44 +02:00
core.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Makefile perf/x86/events: Add an AMD-specific Makefile 2017-01-30 12:01:19 +01:00
msr.c perf/x86/msr: Fix possible Spectre-v1 indexing in the MSR driver 2018-05-05 08:37:29 +02:00
perf_event.h Merge branch 'perf/urgent' into perf/core, to pick up fixes 2018-03-24 09:21:47 +01:00