ALSA: firewire: fix NULL pointer dereference when releasing uninitialized data of...

When calling 'iso_resource_free()' for uninitialized data, this function
causes NULL pointer dereference due to its 'unit' member. This occurs when
unplugging audio and music units on IEEE 1394 bus at failure of card
registration.

This commit fixes the bug. The bug exists since kernel v4.5.

Fixes: 324540c4e05c ('ALSA: fireface: postpone sound card registration') at v4.12
Fixes: 8865a31e0fd8 ('ALSA: firewire-motu: postpone sound card registration') at v4.12
Fixes: b610386c8afb ('ALSA: firewire-tascam: deleyed registration of sound card') at v4.7
Fixes: 86c8dd7f4da3 ('ALSA: firewire-digi00x: delayed registration of sound card') at v4.7
Fixes: 6c29230e2a5f ('ALSA: oxfw: delayed registration of sound card') at v4.7
Fixes: 7d3c1d5901aa ('ALSA: fireworks: delayed registration of sound card') at v4.7
Fixes: 04a2c73c97eb ('ALSA: bebob: delayed registration of sound card') at v4.7
Fixes: b59fb1900b4f ('ALSA: dice: postpone card registration') at v4.5
Cc: <stable@vger.kernel.org> # v4.5+
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/firewire/iso-resources.c b/sound/firewire/iso-resources.c
index f0e4d502d60482ae8374cf9f830b739eb9e38753..066b5df666f42d2259b40ee5d21492f9165e4470 100644 (file)
--- a/sound/firewire/iso-resources.c
+++ b/sound/firewire/iso-resources.c
@@ -210,9 +210,14 @@ EXPORT_SYMBOL(fw_iso_resources_update);
  */
 void fw_iso_resources_free(struct fw_iso_resources *r)
 {
-       struct fw_card *card = fw_parent_device(r->unit)->card;
+       struct fw_card *card;
        int bandwidth, channel;
 
+       /* Not initialized. */
+       if (r->unit == NULL)
+               return;
+       card = fw_parent_device(r->unit)->card;
+
        mutex_lock(&r->mutex);
 
        if (r->allocated) {