linux-stable/Documentation/accounting
Suren Baghdasaryan d3e4c61e14 psi: Fix uaf issue when psi trigger is destroyed while being polled
commit a06247c680 upstream.

With write operation on psi files replacing old trigger with a new one,
the lifetime of its waitqueue is totally arbitrary. Overwriting an
existing trigger causes its waitqueue to be freed and pending poll()
will stumble on trigger->event_wait which was destroyed.
Fix this by disallowing to redefine an existing psi trigger. If a write
operation is used on a file descriptor with an already existing psi
trigger, the operation will fail with EBUSY error.
Also bypass a check for psi_disabled in the psi_trigger_destroy as the
flag can be flipped after the trigger is created, leading to a memory
leak.

Fixes: 0e94682b73 ("psi: introduce psi monitor")
Reported-by: syzbot+cdb5dd11c97cc532efad@syzkaller.appspotmail.com
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Analyzed-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220111232309.1786347-1-surenb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-02-01 17:27:01 +01:00
..
cgroupstats.rst Documentation: Replace lkml.org links with lore 2021-01-11 12:47:38 -07:00
delay-accounting.rst delayacct: Add sysctl to enable at runtime 2021-05-12 11:43:25 +02:00
index.rst docs: add some documentation dirs to the driver-api book 2019-07-15 11:03:02 -03:00
psi.rst psi: Fix uaf issue when psi trigger is destroyed while being polled 2022-02-01 17:27:01 +01:00
taskstats-struct.rst docs: accounting: convert to ReST 2019-07-15 09:20:25 -03:00
taskstats.rst docs: accounting: convert to ReST 2019-07-15 09:20:25 -03:00