Commits
Alexander Shishkin committed 00496fe5e09
perf/aux: Fix the aux_output group inheritance fix
Commit
f733c6b508bc ("perf/core: Fix inheritance of aux_output groups")
adds a NULL pointer dereference in case inherit_group() races with
perf_release(), which causes the below crash:
> BUG: kernel NULL pointer dereference, address: 000000000000010b
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 3b203b067 P4D 3b203b067 PUD 3b2040067 PMD 0
> Oops: 0000 [#1] SMP KASAN
> CPU: 0 PID: 315 Comm: exclusive-group Tainted: G B 5.4.0-rc3-00181-g72e1839403cb-dirty #878
> RIP: 0010:perf_get_aux_event+0x86/0x270
> Call Trace:
> ? __perf_read_group_add+0x3b0/0x3b0
> ? __kasan_check_write+0x14/0x20
> ? __perf_event_init_context+0x154/0x170
> inherit_task_group.isra.0.part.0+0x14b/0x170
> perf_event_init_task+0x296/0x4b0
Fix this by skipping over events that are getting closed, in the
inheritance path.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Fixes: f733c6b508bc ("perf/core: Fix inheritance of aux_output groups")
Link: https://lkml.kernel.org/r/20191101151248.47327-1-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>