Re: [PATCH 2/2] SCSI: Fix NULL pointer dereference in runtime PM

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 11/30/2015 11:45 PM, Ken Xue wrote:
The routines in scsi_pm.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 checking q->dev in block layer before
handle runtime PM. Since ses doesn't define any PM callbacks and call
blk_pm_runtime_init(), the crash won't occur.

This fixes Bugzilla #101371.
https://bugzilla.kernel.org/show_bug.cgi?id=101371

More discussion can be found from below link.
http://marc.info/?l=linux-scsi&m=144163730531875&w=2


Added for 4.4, thanks.

--
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]