ALSA: usb-audio: Fix possible NULL pointer dereference in snd_usb_pcm_has_fixed_rate()

[ Upstream commit 92a9c0ad86d47ff4cce899012e355c400f02cfb8 ]

The subs function argument may be NULL, so do not use it before the NULL check.

Fixes: 291e9da91403 ("ALSA: usb-audio: Always initialize fixed_rate in snd_usb_find_implicit_fb_sync_format()")
Reported-by: coverity-bot <keescook@chromium.org>
Link: https://lore.kernel.org/alsa-devel/202301121424.4A79A485@keescook/
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230113085311.623325-1-perex@perex.cz
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 2983800..2c5765c 100644 (file)
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -160,11 +160,12 @@ find_substream_format(struct snd_usb_substream *subs,
 bool snd_usb_pcm_has_fixed_rate(struct snd_usb_substream *subs)
 {
        const struct audioformat *fp;
-       struct snd_usb_audio *chip = subs->stream->chip;
+       struct snd_usb_audio *chip;
        int rate = -1;
 
        if (!subs)
                return false;
+       chip = subs->stream->chip;
        if (!(chip->quirk_flags & QUIRK_FLAG_FIXED_RATE))
                return false;
        list_for_each_entry(fp, &subs->fmt_list, list) {