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From: Tzung-Bi Shih <tzungbi@google.com>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Cheng-Yi Chiang <cychiang@chromium.org>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>, Jaroslav Kysela <perex@perex.cz>,
	Takashi Iwai <tiwai@suse.com>, Benson Leung <bleung@chromium.org>,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Guenter Roeck <groeck@chromium.org>,
	ALSA development <alsa-devel@alsa-project.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ASoC: cros_ec_codec: fix uninitialized memory read
Date: Fri, 4 Dec 2020 10:56:06 +0800	[thread overview]
Message-ID: <CA+Px+wWmJrS46TzWgKWiufJH7ryB+mOH7H4xfGZex2j=NutfLA@mail.gmail.com> (raw)
In-Reply-To: <20201203225458.1477830-1-arnd@kernel.org>

On Fri, Dec 4, 2020 at 6:55 AM Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> gcc points out a memory area that is copied to a device
> but not initialized:
>
> sound/soc/codecs/cros_ec_codec.c: In function 'i2s_rx_event':
> arch/x86/include/asm/string_32.h:83:20: error: '*((void *)&p+4)' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>    83 |   *((int *)to + 1) = *((int *)from + 1);
>
> Initialize all the unused fields to zero.
>
> Fixes: 727f1c71c780 ("ASoC: cros_ec_codec: refactor I2S RX")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Tzung-Bi Shih <tzungbi@google.com>

In the case in i2s_rx_event(), only the "cmd" member is used.  But it
is fine to please the compiler.

struct __ec_align4 ec_param_ec_codec_i2s_rx {
        uint8_t cmd; /* enum ec_codec_i2s_rx_subcmd */
        uint8_t reserved[3];

        union {
            ...
        };
};

I am a bit curious about, in other use cases of
ec_param_ec_codec_i2s_rx, why the compiler doesn't complain about
uninitialization of the "reserved" member?

  reply	other threads:[~2020-12-04  2:57 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-03 22:54 Arnd Bergmann
2020-12-04  2:56 ` Tzung-Bi Shih [this message]
2020-12-04  8:28   ` Arnd Bergmann
2020-12-04  9:05     ` Tzung-Bi Shih
2020-12-04 23:30 ` Mark Brown

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