[PATCH 5.10 168/406] ALSA: ac97: Fix possible error value of *rac97

Greg Kroah-Hartman
2023-09-17T19:31:06Z

From: Su Hui <suhui@nfschina.com>

[ Upstream commit 67de40c9df94037769967ba28c7d951afb45b7fb ]

Before committing 79597c8bf64c, *rac97 always be NULL if there is
an error. When error happens, make sure *rac97 is NULL is safer.

For examble, in snd_vortex_mixer():
err = snd_ac97_mixer(pbus, &ac97, &vortex->codec);
vortex->isquad = ((vortex->codec == NULL) ?
0 : (vortex->codec->ext_id&0x80));
If error happened but vortex->codec isn't NULL, this may cause some
problems.

Move the judgement order to be clearer and better.

Fixes: 79597c8bf64c ("ALSA: ac97: Fix possible NULL dereference in snd_ac97_mixer")
Suggested-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Su Hui <suhui@nfschina.com>
Link: https://lore.kernel.org/r/20230823025212.1000961-1-suhui@nfschina.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/pci/ac97/ac97_codec.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/sound/pci/ac97/ac97_codec.c b/sound/pci/ac97/ac97_codec.c
index e18572eae5e01..d894dcdf38f4c 100644
--- a/sound/pci/ac97/ac97_codec.c
+++ b/sound/pci/ac97/ac97_codec.c
@@ -2007,10 +2007,9 @@ int snd_ac97_mixer(struct snd_ac97_bus *bus, struct snd_ac97_template *template,
.dev_disconnect = snd_ac97_dev_disconnect,
};

- if (!rac97)
- return -EINVAL;
- if (snd_BUG_ON(!bus || !template))
+ if (snd_BUG_ON(!bus || !template || !rac97))
return -EINVAL;
+ *rac97 = NULL;
if (snd_BUG_ON(template->num >= 4))
return -EINVAL;
if (bus->codec[template->num])
--
2.40.1