The function send_packet() has a race condition as follows:
func send_packet()
{
// do work
call usb_submit_urb()
mutex_unlock()
wait_for_event_interruptible() <-- lock gone
mutex_lock()
}
func vfd_write()
{
mutex_lock()
call send_packet() <- prev call is not completed
mutex_unlock()
}
When the mutex is unlocked and the function send_packet() waits for the
call to complete, vfd_write() can start another call, which leads to the
"URB submitted while active" warning in usb_submit_urb().
Fix this by removing the mutex_unlock() call in send_packet() and using
mutex_lock_interruptible().
Fixes: 21677cfc562a ("V4L/DVB: ir-core: add imon driver")
Link: https://syzkaller.appspot.com/bug?id=e378e6a51fbe6c5cc43e34f131cc9a315ef0337e
Reported-by: [email protected]
Signed-off-by: Gautam Menghani <[email protected]>
---
drivers/media/rc/imon.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/media/rc/imon.c b/drivers/media/rc/imon.c
index 735b925da998..91d8056666ec 100644
--- a/drivers/media/rc/imon.c
+++ b/drivers/media/rc/imon.c
@@ -646,15 +646,14 @@ static int send_packet(struct imon_context *ictx)
pr_err_ratelimited("error submitting urb(%d)\n", retval);
} else {
/* Wait for transmission to complete (or abort) */
- mutex_unlock(&ictx->lock);
retval = wait_for_completion_interruptible(
&ictx->tx.finished);
if (retval) {
usb_kill_urb(ictx->tx_urb);
pr_err_ratelimited("task interrupted\n");
}
- mutex_lock(&ictx->lock);
+ ictx->tx.busy = false;
retval = ictx->tx.status;
if (retval)
pr_err_ratelimited("packet tx failed (%d)\n", retval);
@@ -955,7 +954,8 @@ static ssize_t vfd_write(struct file *file, const char __user *buf,
if (ictx->disconnected)
return -ENODEV;
- mutex_lock(&ictx->lock);
+ if (mutex_lock_interruptible(&ictx->lock))
+ return -ERESTARTSYS;
if (!ictx->dev_present_intf0) {
pr_err_ratelimited("no iMON device present\n");
--
2.34.1
On Wed, Oct 19, 2022 at 10:32:14AM +0530, Gautam Menghani wrote:
> The function send_packet() has a race condition as follows:
> func send_packet()
> {
> // do work
> call usb_submit_urb()
> mutex_unlock()
> wait_for_event_interruptible() <-- lock gone
> mutex_lock()
> }
>
> func vfd_write()
> {
> mutex_lock()
> call send_packet() <- prev call is not completed
> mutex_unlock()
> }
>
> When the mutex is unlocked and the function send_packet() waits for the
> call to complete, vfd_write() can start another call, which leads to the
> "URB submitted while active" warning in usb_submit_urb().
> Fix this by removing the mutex_unlock() call in send_packet() and using
> mutex_lock_interruptible().
>
> Fixes: 21677cfc562a ("V4L/DVB: ir-core: add imon driver")
> Link: https://syzkaller.appspot.com/bug?id=e378e6a51fbe6c5cc43e34f131cc9a315ef0337e
> Reported-by: [email protected]
>
> Signed-off-by: Gautam Menghani <[email protected]>
> ---
> drivers/media/rc/imon.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/rc/imon.c b/drivers/media/rc/imon.c
> index 735b925da998..91d8056666ec 100644
> --- a/drivers/media/rc/imon.c
> +++ b/drivers/media/rc/imon.c
> @@ -646,15 +646,14 @@ static int send_packet(struct imon_context *ictx)
> pr_err_ratelimited("error submitting urb(%d)\n", retval);
> } else {
> /* Wait for transmission to complete (or abort) */
> - mutex_unlock(&ictx->lock);
> retval = wait_for_completion_interruptible(
> &ictx->tx.finished);
> if (retval) {
> usb_kill_urb(ictx->tx_urb);
> pr_err_ratelimited("task interrupted\n");
> }
> - mutex_lock(&ictx->lock);
>
> + ictx->tx.busy = false;
> retval = ictx->tx.status;
> if (retval)
> pr_err_ratelimited("packet tx failed (%d)\n", retval);
> @@ -955,7 +954,8 @@ static ssize_t vfd_write(struct file *file, const char __user *buf,
> if (ictx->disconnected)
> return -ENODEV;
>
> - mutex_lock(&ictx->lock);
> + if (mutex_lock_interruptible(&ictx->lock))
> + return -ERESTARTSYS;
>
> if (!ictx->dev_present_intf0) {
> pr_err_ratelimited("no iMON device present\n");
> --
> 2.34.1
>
Hi,
Please review the above fix and let me know if any changes are required.
Thanks,
Gautam
On Mon, Oct 31, 2022 at 10:20:15AM +0530, Gautam Menghani wrote:
> On Wed, Oct 19, 2022 at 10:32:14AM +0530, Gautam Menghani wrote:
> > The function send_packet() has a race condition as follows:
> > func send_packet()
> > {
> > // do work
> > call usb_submit_urb()
> > mutex_unlock()
> > wait_for_event_interruptible() <-- lock gone
> > mutex_lock()
> > }
> >
> > func vfd_write()
> > {
> > mutex_lock()
> > call send_packet() <- prev call is not completed
> > mutex_unlock()
> > }
> >
> > When the mutex is unlocked and the function send_packet() waits for the
> > call to complete, vfd_write() can start another call, which leads to the
> > "URB submitted while active" warning in usb_submit_urb().
> > Fix this by removing the mutex_unlock() call in send_packet() and using
> > mutex_lock_interruptible().
> >
> > Fixes: 21677cfc562a ("V4L/DVB: ir-core: add imon driver")
> > Link: https://syzkaller.appspot.com/bug?id=e378e6a51fbe6c5cc43e34f131cc9a315ef0337e
> > Reported-by: [email protected]
> >
> > Signed-off-by: Gautam Menghani <[email protected]>
> > ---
> > drivers/media/rc/imon.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/media/rc/imon.c b/drivers/media/rc/imon.c
> > index 735b925da998..91d8056666ec 100644
> > --- a/drivers/media/rc/imon.c
> > +++ b/drivers/media/rc/imon.c
> > @@ -646,15 +646,14 @@ static int send_packet(struct imon_context *ictx)
> > pr_err_ratelimited("error submitting urb(%d)\n", retval);
> > } else {
> > /* Wait for transmission to complete (or abort) */
> > - mutex_unlock(&ictx->lock);
> > retval = wait_for_completion_interruptible(
> > &ictx->tx.finished);
> > if (retval) {
> > usb_kill_urb(ictx->tx_urb);
> > pr_err_ratelimited("task interrupted\n");
> > }
> > - mutex_lock(&ictx->lock);
> >
> > + ictx->tx.busy = false;
> > retval = ictx->tx.status;
> > if (retval)
> > pr_err_ratelimited("packet tx failed (%d)\n", retval);
> > @@ -955,7 +954,8 @@ static ssize_t vfd_write(struct file *file, const char __user *buf,
> > if (ictx->disconnected)
> > return -ENODEV;
> >
> > - mutex_lock(&ictx->lock);
> > + if (mutex_lock_interruptible(&ictx->lock))
> > + return -ERESTARTSYS;
> >
> > if (!ictx->dev_present_intf0) {
> > pr_err_ratelimited("no iMON device present\n");
> > --
> > 2.34.1
> >
>
> Hi,
>
> Please review the above fix and let me know if any changes are required.
>
> Thanks,
> Gautam
Hi,
Please review this patch and let me know if this patch needs any changes.
Thanks,
Gautam