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io_uring: disallow modification of rsrc_data during quiesce

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commit 80912cef18f16f8fe59d1fb9548d4364342be360 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dylan Yudaken 2022-02-22 08:17:51 -08:00 committed by Greg Kroah-Hartman
parent 7c83437fb3
commit 0d773aaf5a
1 changed files with 9 additions and 1 deletions
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10
fs/io_uring.c
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@ -7818,7 +7818,15 @@ static int io_rsrc_ref_quiesce(struct io_rsrc_data *data, struct io_ring_ctx *ct
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);