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SCSI: Fix NULL pointer dereference in runtime PM

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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 <stern@rowland.harvard.edu>
Reported-by: Stanisław Pitucha <viraptor@gmail.com>
Reported-by: Ilan Cohen <ilanco@gmail.com>
Tested-by: Ilan Cohen <ilanco@gmail.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <JBottomley@Odin.com>
This commit is contained in:
Alan Stern 2015-08-17 11:02:42 -04:00 committed by James Bottomley
parent db196935d9
commit 49718f0fb8
1 changed files with 11 additions and 11 deletions
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22
drivers/scsi/scsi_pm.c
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@ -217,15 +217,15 @@ static int sdev_runtime_suspend(struct device *dev)
{ {
const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
struct scsi_device *sdev = to_scsi_device(dev); struct scsi_device *sdev = to_scsi_device(dev);
int err; int err = 0;
err = blk_pre_runtime_suspend(sdev->request_queue); if (pm && pm->runtime_suspend) {
if (err) err = blk_pre_runtime_suspend(sdev->request_queue);
return err; if (err)
if (pm && pm->runtime_suspend) return err;
err = pm->runtime_suspend(dev); err = pm->runtime_suspend(dev);
blk_post_runtime_suspend(sdev->request_queue, err); blk_post_runtime_suspend(sdev->request_queue, err);
}
return err; return err;
} }
@ -248,11 +248,11 @@ static int sdev_runtime_resume(struct device *dev)
const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
int err = 0; 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); err = pm->runtime_resume(dev);
blk_post_runtime_resume(sdev->request_queue, err); blk_post_runtime_resume(sdev->request_queue, err);
}
return err; return err;
} }