ALSA: usb-audio: 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.

Signed-off-by: Chengfeng Ye <cyeaa@connect.ust.hk>
Link: https://lore.kernel.org/r/20211024111736.11342-1-cyeaa@connect.ust.hk
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/clock.c b/sound/usb/clock.c
index 7dd71d3..4dfe764 100644 (file)
--- 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