diff options
| author | Shigeru Yoshida <syoshida@redhat.com> | 2022-09-07 19:35:02 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-09-08 17:41:36 +0300 |
| commit | 1de7c3cf48fc41cd95adb12bd1ea9033a917798a (patch) | |
| tree | 98a8fdc93e3b47b563469407fb77b0aa8f7d260e /drivers/block | |
| parent | 48c033314f372478548203c583529f53080fd078 (diff) | |
| download | linux-1de7c3cf48fc41cd95adb12bd1ea9033a917798a.tar.xz | |
nbd: Fix hung when signal interrupts nbd_start_device_ioctl()
syzbot reported hung task [1]. The following program is a simplified
version of the reproducer:
int main(void)
{
int sv[2], fd;
if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv) < 0)
return 1;
if ((fd = open("/dev/nbd0", 0)) < 0)
return 1;
if (ioctl(fd, NBD_SET_SIZE_BLOCKS, 0x81) < 0)
return 1;
if (ioctl(fd, NBD_SET_SOCK, sv[0]) < 0)
return 1;
if (ioctl(fd, NBD_DO_IT) < 0)
return 1;
return 0;
}
When signal interrupt nbd_start_device_ioctl() waiting the condition
atomic_read(&config->recv_threads) == 0, the task can hung because it
waits the completion of the inflight IOs.
This patch fixes the issue by clearing queue, not just shutdown, when
signal interrupt nbd_start_device_ioctl().
Link: https://syzkaller.appspot.com/bug?id=7d89a3ffacd2b83fdd39549bc4d8e0a89ef21239 [1]
Reported-by: syzbot+38e6c55d4969a14c1534@syzkaller.appspotmail.com
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20220907163502.577561-1-syoshida@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/nbd.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 2a709daefbc4..2a2a1d996a57 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1413,10 +1413,12 @@ static int nbd_start_device_ioctl(struct nbd_device *nbd) mutex_unlock(&nbd->config_lock); ret = wait_event_interruptible(config->recv_wq, atomic_read(&config->recv_threads) == 0); - if (ret) + if (ret) { sock_shutdown(nbd); - flush_workqueue(nbd->recv_workq); + nbd_clear_que(nbd); + } + flush_workqueue(nbd->recv_workq); mutex_lock(&nbd->config_lock); nbd_bdev_reset(nbd); /* user requested, ignore socket errors */ |