[PATCH] ublk: fail to start device if queue setup is interrupted

[PATCH] ublk: fail to start device if queue setup is interrupted

[Ming Lei]

In ublk_ctrl_start_dev(), if wait_for_completion_interruptible() is
interrupted by signal, queues aren't setup successfully yet, so we
have to fail UBLK_CMD_START_DEV, otherwise kernel oops can be triggered.

Reported by German when working for supporting ublk on qemu-storage-deamon
which requires single thread ublk daemon.

Fixes: 71f28f3136af ("ublk_drv: add io_uring based userspace block driver")
Reported-by: German Maglione <gmaglione@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/block/ublk_drv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 1c823750c95a..7938221f4f7e 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1847,7 +1847,8 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd)
 	if (ublksrv_pid <= 0)
 		return -EINVAL;
 
-	wait_for_completion_interruptible(&ub->completion);
+	if (wait_for_completion_interruptible(&ub->completion) != 0)
+		return -EINTR;
 
 	schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
 
-- 
2.40.1

Re: [PATCH] ublk: fail to start device if queue setup is interrupted

[Stefano Garzarella]

On Wed, Jul 26, 2023 at 07:39:01PM +0800, Ming Lei wrote:
>In ublk_ctrl_start_dev(), if wait_for_completion_interruptible() is
>interrupted by signal, queues aren't setup successfully yet, so we
>have to fail UBLK_CMD_START_DEV, otherwise kernel oops can be triggered.
>
>Reported by German when working for supporting ublk on qemu-storage-deamon
>which requires single thread ublk daemon.
>
>Fixes: 71f28f3136af ("ublk_drv: add io_uring based userspace block driver")
>Reported-by: German Maglione <gmaglione@redhat.com>
>Signed-off-by: Ming Lei <ming.lei@redhat.com>
>---
> drivers/block/ublk_drv.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
>index 1c823750c95a..7938221f4f7e 100644
>--- a/drivers/block/ublk_drv.c
>+++ b/drivers/block/ublk_drv.c
>@@ -1847,7 +1847,8 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd)
> 	if (ublksrv_pid <= 0)
> 		return -EINVAL;
>
>-	wait_for_completion_interruptible(&ub->completion);
>+	if (wait_for_completion_interruptible(&ub->completion) != 0)
>+		return -EINTR;

Should we do somenthig similar also in ublk_ctrl_end_recovery()?

Maybe also in ublk_ctrl_del_dev() we can return -EINTR.

Thanks,
Stefano

Re: [PATCH] ublk: fail to start device if queue setup is interrupted

[Ming Lei]

On Wed, Jul 26, 2023 at 03:30:34PM +0200, Stefano Garzarella wrote:
> On Wed, Jul 26, 2023 at 07:39:01PM +0800, Ming Lei wrote:
> > In ublk_ctrl_start_dev(), if wait_for_completion_interruptible() is
> > interrupted by signal, queues aren't setup successfully yet, so we
> > have to fail UBLK_CMD_START_DEV, otherwise kernel oops can be triggered.
> > 
> > Reported by German when working for supporting ublk on qemu-storage-deamon
> > which requires single thread ublk daemon.
> > 
> > Fixes: 71f28f3136af ("ublk_drv: add io_uring based userspace block driver")
> > Reported-by: German Maglione <gmaglione@redhat.com>
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> > drivers/block/ublk_drv.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> > index 1c823750c95a..7938221f4f7e 100644
> > --- a/drivers/block/ublk_drv.c
> > +++ b/drivers/block/ublk_drv.c
> > @@ -1847,7 +1847,8 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd)
> > 	if (ublksrv_pid <= 0)
> > 		return -EINVAL;
> > 
> > -	wait_for_completion_interruptible(&ub->completion);
> > +	if (wait_for_completion_interruptible(&ub->completion) != 0)
> > +		return -EINTR;
> 
> Should we do somenthig similar also in ublk_ctrl_end_recovery()?

Good catch, ublk_ctrl_end_recovery() do need similar handling, otherwise
similar kernel oops may be triggered too.

> 
> Maybe also in ublk_ctrl_del_dev() we can return -EINTR.
 
It doesn't matter for ublk_ctrl_del_dev() given it just waits for
existed users, but still good to return -EINTR to user.


Thanks,
Ming