[3.16.y-ckt stable] Patch "SCSI: Fix NULL pointer dereference in runtime PM" has been added to staging queue
Luis Henriques
luis.henriques at canonical.com
Thu Sep 3 10:37:57 UTC 2015
This is a note to let you know that I have just added a patch titled
SCSI: Fix NULL pointer dereference in runtime PM
to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue
This patch is scheduled to be released in version 3.16.7-ckt17.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From e12bb4087e4c324f492b120a8ece878f9bc01406 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern at rowland.harvard.edu>
Date: Mon, 17 Aug 2015 11:02:42 -0400
Subject: SCSI: Fix NULL pointer dereference in runtime PM
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
commit 49718f0fb8c9af192b33d8af3a2826db04025371 upstream.
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 at rowland.harvard.edu>
Reported-by: Stanisław Pitucha <viraptor at gmail.com>
Reported-by: Ilan Cohen <ilanco at gmail.com>
Tested-by: Ilan Cohen <ilanco at gmail.com>
Reviewed-by: Johannes Thumshirn <jthumshirn at suse.de>
Signed-off-by: James Bottomley <JBottomley at Odin.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
drivers/scsi/scsi_pm.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
index 7454498c4091..a2dcf6a54ec6 100644
--- a/drivers/scsi/scsi_pm.c
+++ b/drivers/scsi/scsi_pm.c
@@ -219,15 +219,15 @@ static int sdev_runtime_suspend(struct device *dev)
{
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;
}
@@ -250,11 +250,11 @@ static int sdev_runtime_resume(struct device *dev)
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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