diff options
| author | Dylan Yudaken <dylany@fb.com> | 2022-02-22 19:17:51 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-02-22 19:57:32 +0300 |
| commit | 80912cef18f16f8fe59d1fb9548d4364342be360 (patch) | |
| tree | de6b869f7af34d8f31912d2f7c1b3326938fba1d /fs/io_uring.c | |
| parent | 228339662b398a59b3560cd571deb8b25b253c7e (diff) | |
| download | linux-80912cef18f16f8fe59d1fb9548d4364342be360.tar.xz | |
io_uring: disallow modification of rsrc_data during quiesce
io_rsrc_ref_quiesce will unlock the uring while it waits for references to
the io_rsrc_data to be killed.
There are other places to the data that might add references to data via
calls to io_rsrc_node_switch.
There is a race condition where this reference can be added after the
completion has been signalled. At this point the io_rsrc_ref_quiesce call
will wake up and relock the uring, assuming the data is unused and can be
freed - although it is actually being used.
To fix this check in io_rsrc_ref_quiesce if a resource has been revived.
Reported-by: syzbot+ca8bf833622a1662745b@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220222161751.995746-1-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
| -rw-r--r-- | fs/io_uring.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 928446fe1319..4715980e9015 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7926,7 +7926,15 @@ static __cold int io_rsrc_ref_quiesce(struct io_rsrc_data *data, ret = wait_for_completion_interruptible(&data->done); if (!ret) { mutex_lock(&ctx->uring_lock); - break; + if (atomic_read(&data->refs) > 0) { + /* + * it has been revived by another thread while + * we were unlocked + */ + mutex_unlock(&ctx->uring_lock); + } else { + break; + } } atomic_inc(&data->refs); |