Patch "stm class: Fix a use-after-free" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    stm class: Fix a use-after-free

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     stm-class-fix-a-use-after-free.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From fd085bb1766d6a598f53af2308374a546a49775a Mon Sep 17 00:00:00 2001
From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Date: Tue, 19 Sep 2017 18:47:40 +0300
Subject: stm class: Fix a use-after-free

From: Alexander Shishkin <alexander.shishkin@linux.intel.com>

commit fd085bb1766d6a598f53af2308374a546a49775a upstream.

For reasons unknown, the stm_source removal path uses device_destroy()
to kill the underlying device object. Because device_destroy() uses
devt to look for the device to destroy and the fact that stm_source
devices don't have one (or all have the same one), it just picks the
first device in the class, which may well be the wrong one.

That is, loading stm_console and stm_heartbeat and then removing both
will die in dereferencing a freed object.

Since this should have been device_unregister() in the first place,
use it instead of device_destroy().

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Fixes: 7bd1d4093c2 ("stm class: Introduce an abstraction for System Trace Module devices")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/hwtracing/stm/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -1119,7 +1119,7 @@ void stm_source_unregister_device(struct
 
 	stm_source_link_drop(src);
 
-	device_destroy(&stm_source_class, src->dev.devt);
+	device_unregister(&src->dev);
 }
 EXPORT_SYMBOL_GPL(stm_source_unregister_device);
 


Patches currently in stable-queue which might be from alexander.shishkin@linux.intel.com are

queue-4.9/stm-class-fix-a-use-after-free.patch
queue-4.9/intel_th-pci-add-lewisburg-pch-support.patch
queue-4.9/intel_th-pci-add-cedar-fork-pch-support.patch