[PATCH 5.13 23/24] ALSA: pcm: fix divide error in snd_pcm_lib_ioctl

[Greg Kroah-Hartman]

From: Zubin Mithra <zsm@xxxxxxxxxxxx>

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@xxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <groeck@xxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210827153735.789452-1-zsm@xxxxxxxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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
@@ -1746,7 +1746,7 @@ 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;
 }