ALSA: Allow pass NULL dev for snd_pci_quirk_lookup()

Add a NULL check in snd_pci_quirk_lookup() so that NULL can be passed
as a pci_dev pointer.  This fixes the possible NULL dereferences in
HD-audio drivers.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/sound/core/misc.c b/sound/core/misc.c
index 30e027ecf4da..f2e8226c88fb 100644
--- a/sound/core/misc.c
+++ b/sound/core/misc.c
@@ -145,6 +145,8 @@ EXPORT_SYMBOL(snd_pci_quirk_lookup_id);
 const struct snd_pci_quirk *
 snd_pci_quirk_lookup(struct pci_dev *pci, const struct snd_pci_quirk *list)
 {
+        if (!pci)
+                return NULL;
         return snd_pci_quirk_lookup_id(pci->subsystem_vendor,
                                        pci->subsystem_device,
                                        list);