Patch "ALSA: hda - fix use-after-free after module unload" has been added to the 4.4-stable tree

Patch "ALSA: hda - fix use-after-free after module unload" has been added to the 4.4-stable tree

[gregkh]

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

    ALSA: hda - fix use-after-free after module unload

to the 4.4-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:
     alsa-hda-fix-use-after-free-after-module-unload.patch
and it can be found in the queue-4.4 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 ab58d8cc870ef3f0771c197700441936898d1f1d Mon Sep 17 00:00:00 2001
From: Peter Wu <peter@lekensteyn.nl>
Date: Mon, 11 Jul 2016 19:51:06 +0200
Subject: ALSA: hda - fix use-after-free after module unload

From: Peter Wu <peter@lekensteyn.nl>

commit ab58d8cc870ef3f0771c197700441936898d1f1d upstream.

register_vga_switcheroo() sets the PM ops from the hda structure which
is freed later in azx_free. Make sure that these ops are cleared.

Caught by KASAN, initially noticed due to a general protection fault.

Fixes: 246efa4a072f ("snd/hda: add runtime suspend/resume on optimus support (v4)")
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 sound/pci/hda/hda_intel.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1256,8 +1256,10 @@ static int azx_free(struct azx *chip)
 	if (use_vga_switcheroo(hda)) {
 		if (chip->disabled && hda->probe_continued)
 			snd_hda_unlock_devices(&chip->bus);
-		if (hda->vga_switcheroo_registered)
+		if (hda->vga_switcheroo_registered) {
 			vga_switcheroo_unregister_client(chip->pci);
+			vga_switcheroo_fini_domain_pm_ops(chip->card->dev);
+		}
 	}
 
 	if (bus->chip_init) {


Patches currently in stable-queue which might be from peter@lekensteyn.nl are

queue-4.4/alsa-hda-fix-use-after-free-after-module-unload.patch