Commit 80912cef authored by Dylan Yudaken's avatar Dylan Yudaken Committed by Jens Axboe

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: default avatarDylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220222161751.995746-1-dylany@fb.comSigned-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 22833966
...@@ -7926,7 +7926,15 @@ static __cold int io_rsrc_ref_quiesce(struct io_rsrc_data *data, ...@@ -7926,7 +7926,15 @@ static __cold int io_rsrc_ref_quiesce(struct io_rsrc_data *data,
ret = wait_for_completion_interruptible(&data->done); ret = wait_for_completion_interruptible(&data->done);
if (!ret) { if (!ret) {
mutex_lock(&ctx->uring_lock); 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); atomic_inc(&data->refs);
......
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