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    Subject[PATCH 5.2 062/313] ALSA: i2c: ak4xxx-adda: Fix a possible null pointer dereference in build_adc_controls()
    Date
    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


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