Alan Stern <st...@rowland.harvard.edu> writes:
> The routines in scsi_rpm.c assume that if a runtime-PM callback is
> invoked for a SCSI device, it can only mean that the device's driver
> has asked the block layer to handle the runtime power management (by
> calling blk_pm_runtime_init(), which among other things sets q->dev).
>
> However, this assumption turns out to be wrong for things like the ses
> driver. Normally ses devices are not allowed to do runtime PM, but
> userspace can override this setting. If this happens, the kernel gets
> a NULL pointer dereference when blk_post_runtime_resume() tries to use
> the uninitialized q->dev pointer.
>
> This patch fixes the problem by calling the block layer's runtime-PM
> routines only if the device's driver really does have a runtime-PM
> callback routine. Since ses doesn't define any such callbacks, the
> crash won't occur.
>
> This fixes Bugzilla #101371.
>
> Signed-off-by: Alan Stern <st...@rowland.harvard.edu>
> Reported-by: Stanisław Pitucha <virap...@gmail.com>
> Reported-by: Ilan Cohen <ila...@gmail.com>
> Tested-by: Ilan Cohen <ila...@gmail.com>
>
> ---
>
>
> [as1784]
>
>
> drivers/scsi/scsi_pm.c | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
>
> Index: usb-4.0/drivers/scsi/scsi_pm.c
> ===================================================================
> --- usb-4.0.orig/drivers/scsi/scsi_pm.c
> +++ usb-4.0/drivers/scsi/scsi_pm.c
> @@ -217,15 +217,15 @@ static int sdev_runtime_suspend(struct d
> {
> const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
> struct scsi_device *sdev = to_scsi_device(dev);
> - int err;
> + int err = 0;
>
> - err = blk_pre_runtime_suspend(sdev->request_queue);
> - if (err)
> - return err;
> - if (pm && pm->runtime_suspend)
> + if (pm && pm->runtime_suspend) {
> + err = blk_pre_runtime_suspend(sdev->request_queue);
> + if (err)
> + return err;
> err = pm->runtime_suspend(dev);
> - blk_post_runtime_suspend(sdev->request_queue, err);
> -
> + blk_post_runtime_suspend(sdev->request_queue, err);
> + }
> return err;
> }
>
> @@ -248,11 +248,11 @@ static int sdev_runtime_resume(struct de
> const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
> int err = 0;
>
> - blk_pre_runtime_resume(sdev->request_queue);
> - if (pm && pm->runtime_resume)
> + if (pm && pm->runtime_resume) {
> + blk_pre_runtime_resume(sdev->request_queue);
> err = pm->runtime_resume(dev);
> - blk_post_runtime_resume(sdev->request_queue, err);
> -
> + blk_post_runtime_resume(sdev->request_queue, err);
> + }
> return err;
> }
>
>
> --
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Reviewed-by: Johannes Thumshirn <jthumsh...@suse.de>
--
Johannes Thumshirn Storage
jthumsh...@suse.de +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
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