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| author | Suren Baghdasaryan <surenb@google.com> | 2022-01-12 02:23:09 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-02-01 19:27:01 +0300 |
| commit | d3e4c61e143e69671803ef3f52140cf7a7258ee7 (patch) | |
| tree | 70678e26ecc81152a6e3e317bb70c25f4ebd614f /include | |
| parent | b17cb93dda1dcdc9737c8b334e850c18dc6b0b7d (diff) | |
| download | linux-d3e4c61e143e69671803ef3f52140cf7a7258ee7.tar.xz | |
psi: Fix uaf issue when psi trigger is destroyed while being polled
commit a06247c6804f1a7c86a2e5398a4c1f1db1471848 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: 0e94682b73bf ("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>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/psi.h | 2 | ||||
| -rw-r--r-- | include/linux/psi_types.h | 3 |
2 files changed, 1 insertions, 4 deletions
diff --git a/include/linux/psi.h b/include/linux/psi.h index 65eb1476ac70..74f7148dfb9f 100644 --- a/include/linux/psi.h +++ b/include/linux/psi.h @@ -32,7 +32,7 @@ void cgroup_move_task(struct task_struct *p, struct css_set *to); struct psi_trigger *psi_trigger_create(struct psi_group *group, char *buf, size_t nbytes, enum psi_res res); -void psi_trigger_replace(void **trigger_ptr, struct psi_trigger *t); +void psi_trigger_destroy(struct psi_trigger *t); __poll_t psi_trigger_poll(void **trigger_ptr, struct file *file, poll_table *wait); diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h index 0819c82dba92..6f190002a202 100644 --- a/include/linux/psi_types.h +++ b/include/linux/psi_types.h @@ -140,9 +140,6 @@ struct psi_trigger { * events to one per window */ u64 last_event_time; - - /* Refcounting to prevent premature destruction */ - struct kref refcount; }; struct psi_group { |