linux-stable/kernel/events
Peter Zijlstra 22fb297422 perf: Fix sys_perf_event_open() race against self
commit 3ac6487e58 upstream.

Norbert reported that it's possible to race sys_perf_event_open() such
that the looser ends up in another context from the group leader,
triggering many WARNs.

The move_group case checks for races against itself, but the
!move_group case doesn't, seemingly relying on the previous
group_leader->ctx == ctx check. However, that check is racy due to not
holding any locks at that time.

Therefore, re-check the result after acquiring locks and bailing
if they no longer match.

Additionally, clarify the not_move_group case from the
move_group-vs-move_group race.

Fixes: f63a8daa58 ("perf: Fix event->ctx locking")
Reported-by: Norbert Slusarek <nslusarek@gmx.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-25 09:59:02 +02:00
..
callchain.c uaccess: add force_uaccess_{begin,end} helpers 2020-08-12 10:57:59 -07:00
core.c perf: Fix sys_perf_event_open() race against self 2022-05-25 09:59:02 +02:00
hw_breakpoint.c perf/hw_breakpoint: Replace deprecated CPU-hotplug functions 2021-08-26 09:14:36 +02:00
internal.h perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled 2022-04-27 14:41:12 +02:00
Makefile perf/core: allow ftrace for functions in kernel/event/core.c 2021-10-25 22:50:42 -04:00
ring_buffer.c perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled 2022-04-27 14:41:12 +02:00
uprobes.c mm/memcg: Convert mem_cgroup_charge() to take a folio 2021-09-27 09:27:31 -04:00