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

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>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 2f523b08f5762de27cd831d96549ae3a12373b20..8ff15d834ace3e6f64db926118cbe4b8d4ec143a 100644 (file)
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -950,8 +950,10 @@ static int azx_free(struct azx *chip)
        if (use_vga_switcheroo(chip)) {
                if (chip->disabled && chip->bus)
                        snd_hda_unlock_devices(chip->bus);
-               if (chip->vga_switcheroo_registered)
+               if (chip->vga_switcheroo_registered) {
                        vga_switcheroo_unregister_client(chip->pci);
+                       vga_switcheroo_fini_domain_pm_ops(chip->card->dev);
+               }
        }
 
        if (chip->initialized) {