On Wed, Sep 25, 2024 at 04:03:51PM +0530, Mukesh Ojha wrote:
> Multiple call to glink_subdev_stop() for the same remoteproc can happen
> if rproc_stop() fails from Process-A that leaves the rproc state to
> RPROC_CRASHED state later a call to recovery_store from user space in
> Process B triggers rproc_trigger_recovery() of the same remoteproc to
> recover it results in NULL pointer dereference issue in
> qcom_glink_smem_unregister().
>
> Fix it by having a NULL check in glink_subdev_stop().
>
> Process-A Process-B
>
> fatal error interrupt happens
>
> rproc_crash_handler_work()
> mutex_lock_interruptible(&rproc->lock);
> ...
>
> rproc->state = RPROC_CRASHED;
> ...
> mutex_unlock(&rproc->lock);
>
> rproc_trigger_recovery()
> mutex_lock_interruptible(&rproc->lock);
>
> adsp_stop()
> qcom_q6v5_pas 20c00000.remoteproc: failed to shutdown: -22
> remoteproc remoteproc3: can't stop rproc: -22
I presume that at this point this remoteproc is in some undefined state
and the only way to recover is for the user to reboot the machine?
The check for glink->edge avoids one pitfall following this, but I'd
prefer to see a solution that avoids issues in this scenario in the
remoteproc core - rather than working around side effects of this in
different places.
Regards,
Bjorn
> mutex_unlock(&rproc->lock);
>
> echo enabled > /sys/class/remoteproc/remoteprocX/recovery
> recovery_store()
> rproc_trigger_recovery()
> mutex_lock_interruptible(&rproc->lock);
> rproc_stop()
> glink_subdev_stop()
> qcom_glink_smem_unregister() ==|
> |
> V
> Unable to handle kernel NULL pointer dereference
> at virtual address 0000000000000358
>
> Signed-off-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
> ---
> - We can do this NULL check in qcom_glink_smem_unregister() as it is
> exported function however, there is only one user of this. So, doing
> it with current approach should also be fine.
>
> drivers/remoteproc/qcom_common.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/remoteproc/qcom_common.c b/drivers/remoteproc/qcom_common.c
> index 8c8688f99f0a..52d6c9b99fdb 100644
> --- a/drivers/remoteproc/qcom_common.c
> +++ b/drivers/remoteproc/qcom_common.c
> @@ -209,6 +209,9 @@ static void glink_subdev_stop(struct rproc_subdev *subdev, bool crashed)
> {
> struct qcom_rproc_glink *glink = to_glink_subdev(subdev);
>
> + if (!glink->edge)
> + return;
> +
> qcom_glink_smem_unregister(glink->edge);
> glink->edge = NULL;
> }
> --
> 2.34.1
>
>
