linux-kernel - [PATCH] sound/usb: fix null pointer dereference on pointer cs

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Message-Id: <20211024111736.11342-1-cyeaa@connect.ust.hk>
Date:   Sun, 24 Oct 2021 04:17:36 -0700
From:   Chengfeng Ye <cyeaa@...nect.ust.hk>
To:     perex@...ex.cz, tiwai@...e.com, chihhao.chen@...iatek.com,
        damien@...audio.com
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        Chengfeng Ye <cyeaa@...nect.ust.hk>
Subject: [PATCH] sound/usb: fix null pointer dereference on pointer cs_desc

The pointer cs_desc return from snd_usb_find_clock_source could
be null, so there is a potential null pointer dereference issue.
Fix this by adding a null check before dereference.

Fixes: 9ec73005 ("ALSA: usb-audio: Refactoring UAC2/3 clock setup code")
Signed-off-by: Chengfeng Ye <cyeaa@...nect.ust.hk>
---
 sound/usb/clock.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sound/usb/clock.c b/sound/usb/clock.c
index 81d5ce07d548..98345a695dcc 100644
--- a/sound/usb/clock.c
+++ b/sound/usb/clock.c
@@ -496,6 +496,10 @@ int snd_usb_set_sample_rate_v2v3(struct snd_usb_audio *chip,
 	union uac23_clock_source_desc *cs_desc;
 
 	cs_desc = snd_usb_find_clock_source(chip, clock, fmt->protocol);
+
+	if (!cs_desc)
+		return 0;
+
 	if (fmt->protocol == UAC_VERSION_3)
 		bmControls = le32_to_cpu(cs_desc->v3.bmControls);
 	else
-- 
2.17.1