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SubjectRe: [PATCH] ALSA: i2c: ak4xxx-adda: Fix a possible null pointer dereference in build_adc_controls()
On Thu, 25 Jul 2019 10:27:33 +0200,
Jia-Ju Bai wrote:
>
> 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>
> ---
> sound/i2c/other/ak4xxx-adda.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/sound/i2c/other/ak4xxx-adda.c b/sound/i2c/other/ak4xxx-adda.c
> index 5f59316f982a..9a891470e84a 100644
> --- a/sound/i2c/other/ak4xxx-adda.c
> +++ b/sound/i2c/other/ak4xxx-adda.c
> @@ -775,11 +775,13 @@ 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;

The code change itself looks good, but please follow the standard
coding style. In short: please run checkpatch.pl, fix errors (some
warnings may be ignored) and resubmit.


thanks,

Takashi

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