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ALSA: i2c: ak4xxx-adda: Fix a possible null pointer dereference in build_adc_controls()

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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>
This commit is contained in:
Jia-Ju Bai 2019-07-26 10:14:42 +08:00 committed by Takashi Iwai
parent dd65f7e19c
commit 2127c01b7f
1 changed files with 4 additions and 3 deletions
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7
sound/i2c/other/ak4xxx-adda.c
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@ -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;