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([2402:f000:4:72:808::177e]) by smtp.gmail.com with ESMTPSA id b126sm75007442pfa.126.2019.07.25.19.05.40 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 Jul 2019 19:05:42 -0700 (PDT) Subject: Re: [PATCH] ALSA: i2c: ak4xxx-adda: Fix a possible null pointer dereference in build_adc_controls() To: Takashi Iwai Cc: tglx@linutronix.de, gregkh@linuxfoundation.org, perex@perex.cz, rfontana@redhat.com, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org References: <20190725082733.15234-1-baijiaju1990@gmail.com> From: Jia-Ju Bai Message-ID: <5ef03517-a52f-fe24-30e9-62466d4a1319@gmail.com> Date: Fri, 26 Jul 2019 10:05:42 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/7/25 23:52, Takashi Iwai wrote: > 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 >> --- >> 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. Okay, thanks for the advice. I will send a v2 patch. Best wishes, Jia-Ju Bai