[PATCH AUTOSEL 5.3 033/203] ALSA: i2c: ak4xxx-adda: Fix a possible null pointer dereference in build_adc_controls()

Sasha Levin
2019-09-22T19:38:46Z

From: Jia-Ju Bai <baijiaju1990@gmail.com>

[ Upstream commit 2127c01b7f63b06a21559f56a8c81a3c6535bd1a ]

In build_adc_controls(), there is an if statement on line 773 to check
whether ak->adc_info is NULL:
if (! ak->adc_info ||
! ak->adc_info[mixer_ch].switch_name)

When ak->adc_info is NULL, it is used on line 792:
knew.name = ak->adc_info[mixer_ch].selector_name;

Thus, a possible null-pointer dereference may occur.

To fix this bug, referring to lines 773 and 774, ak->adc_info
and ak->adc_info[mixer_ch].selector_name are checked before being used.

This bug is found by a static analysis tool STCheck written by us.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/i2c/other/ak4xxx-adda.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/sound/i2c/other/ak4xxx-adda.c b/sound/i2c/other/ak4xxx-adda.c
index 5f59316f982ae..7d15093844b92 100644
--- a/sound/i2c/other/ak4xxx-adda.c
+++ b/sound/i2c/other/ak4xxx-adda.c
@@ -775,11 +775,12 @@ static int build_adc_controls(struct snd_akm4xxx *ak)
return err;

memset(&knew, 0, sizeof(knew));
- knew.name = ak->adc_info[mixer_ch].selector_name;
- if (!knew.name) {
+ if (!ak->adc_info ||
+ !ak->adc_info[mixer_ch].selector_name) {
knew.name = "Capture Channel";
knew.index = mixer_ch + ak->idx_offset * 2;
- }
+ } else
+ knew.name = ak->adc_info[mixer_ch].selector_name;

knew.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
knew.info = ak4xxx_capture_source_info;
--
2.20.1