Messages in this thread | | | Date | Wed, 12 Jan 2022 11:03:52 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 1/1] psi: Fix uaf issue when psi trigger is destroyed while being polled |
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On Tue, Jan 11, 2022 at 03:23:09PM -0800, Suren Baghdasaryan wrote: > 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: 0e94682b73bf ("psi: introduce psi monitor") > Cc: stable@vger.kernel.org > Reported-by: syzbot+cdb5dd11c97cc532efad@syzkaller.appspotmail.com > Analyzed-by: Eric Biggers <ebiggers@kernel.org> > Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> > Signed-off-by: Suren Baghdasaryan <surenb@google.com> > ---
Thanks, I'll go stick this in sched/urgent unless Linus picks it up himself.
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