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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Zubin Mithra <zsm@chromium.org>,
        Guenter Roeck <groeck@chromium.org>,
        Takashi Iwai <tiwai@suse.de>
Subject: [PATCH 4.19 011/293] ALSA: pcm: fix divide error in snd_pcm_lib_ioctl
Date:   Mon, 20 Sep 2021 18:39:33 +0200
Message-Id: <20210920163933.645576817@linuxfoundation.org>
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From: Zubin Mithra <zsm@chromium.org>

commit f3eef46f0518a2b32ca1244015820c35a22cfe4a upstream.

Syzkaller reported a divide error in snd_pcm_lib_ioctl. fifo_size
is of type snd_pcm_uframes_t(unsigned long). If frame_size
is 0x100000000, the error occurs.

Fixes: a9960e6a293e ("ALSA: pcm: fix fifo_size frame calculation")
Signed-off-by: Zubin Mithra <zsm@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210827153735.789452-1-zsm@chromium.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 sound/core/pcm_lib.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1751,7 +1751,7 @@ static int snd_pcm_lib_ioctl_fifo_size(s
 		channels = params_channels(params);
 		frame_size = snd_pcm_format_size(format, channels);
 		if (frame_size > 0)
-			params->fifo_size /= (unsigned)frame_size;
+			params->fifo_size /= frame_size;
 	}
 	return 0;
 }