linux-kernel - Coverity: snd_usb_pcm_has_fixed_rate(): Null pointer dereferences

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Message-ID: <202301121424.4A79A485@keescook>
Date:   Thu, 12 Jan 2023 14:24:52 -0800
From:   coverity-bot <keescook@...omium.org>
To:     Jaroslav Kysela <perex@...ex.cz>
Cc:     Matteo Martelli <matteomartelli3@...il.com>,
        Colin Ian King <colin.i.king@...il.com>,
        André Kapelrud <a.kapelrud@...il.com>,
        Takashi Iwai <tiwai@...e.com>,
        chihhao chen <chihhao.chen@...iatek.com>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Dan Carpenter <error27@...il.com>, alsa-devel@...a-project.org,
        Takashi Iwai <tiwai@...e.de>, Craig McLure <craig@...ure.net>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        linux-next@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Coverity: snd_usb_pcm_has_fixed_rate(): Null pointer dereferences

Hello!

This is an experimental semi-automated report about issues detected by
Coverity from a scan of next-20230111 as part of the linux-next scan project:
https://scan.coverity.com/projects/linux-next-weekly-scan

You're getting this email because you were associated with the identified
lines of code (noted below) that were touched by commits:

  Mon Jan 9 16:05:21 2023 +0100
    291e9da91403 ("ALSA: usb-audio: Always initialize fixed_rate in snd_usb_find_implicit_fb_sync_format()")

Coverity reported the following:

*** CID 1530547:  Null pointer dereferences  (REVERSE_INULL)
sound/usb/pcm.c:166 in snd_usb_pcm_has_fixed_rate()
160     bool snd_usb_pcm_has_fixed_rate(struct snd_usb_substream *subs)
161     {
162     	const struct audioformat *fp;
163     	struct snd_usb_audio *chip = subs->stream->chip;
164     	int rate = -1;
165
vvv     CID 1530547:  Null pointer dereferences  (REVERSE_INULL)
vvv     Null-checking "subs" suggests that it may be null, but it has already been dereferenced on all paths leading to the check.
166     	if (!subs)
167     		return false;
168     	if (!(chip->quirk_flags & QUIRK_FLAG_FIXED_RATE))
169     		return false;
170     	list_for_each_entry(fp, &subs->fmt_list, list) {
171     		if (fp->rates & SNDRV_PCM_RATE_CONTINUOUS)

If this is a false positive, please let us know so we can mark it as
such, or teach the Coverity rules to be smarter. If not, please make
sure fixes get into linux-next. :) For patches fixing this, please
include these lines (but double-check the "Fixes" first):

Reported-by: coverity-bot <keescook+coverity-bot@...omium.org>
Addresses-Coverity-ID: 1530547 ("Null pointer dereferences")
Fixes: 291e9da91403 ("ALSA: usb-audio: Always initialize fixed_rate in snd_usb_find_implicit_fb_sync_format()")

Thanks for your attention!

-- 
Coverity-bot