linux-kernel - [PATCH 4.4 128/146] ALSA: hda - fix use-after-free after module unload

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Date:	Mon, 25 Jul 2016 13:56:23 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Peter Wu <peter@...ensteyn.nl>,
	Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 4.4 128/146] ALSA: hda - fix use-after-free after module unload

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Wu <peter@...ensteyn.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@...ensteyn.nl>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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) {