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ALSA: fireface: Fix integer overflow in transmit_midi_msg()

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As snd_ff.rx_bytes[] is unsigned int, and NSEC_PER_SEC is 1000000000L,
the second multiplication in

    ff->rx_bytes[port] * 8 * NSEC_PER_SEC / 31250

always overflows on 32-bit platforms, truncating the result.  Fix this
by precalculating "NSEC_PER_SEC / 31250", which is an integer constant.

Note that this assumes ff->rx_bytes[port] <= 16777.

Fixes: 1917429578 ("ALSA: fireface: add transaction support")
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20210111130251.361335-2-geert+renesas@glider.be
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Geert Uytterhoeven 2021-01-11 14:02:50 +01:00 committed by Takashi Iwai
parent 615d435400
commit e7c22eeaff
1 changed files with 1 additions and 1 deletions
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2
sound/firewire/fireface/ff-transaction.c
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@ -88,7 +88,7 @@ static void transmit_midi_msg(struct snd_ff *ff, unsigned int port)
/* Set interval to next transaction. */
ff->next_ktime[port] = ktime_add_ns(ktime_get(),
ff->rx_bytes[port] * 8 * NSEC_PER_SEC / 31250);
ff->rx_bytes[port] * 8 * (NSEC_PER_SEC / 31250));
if (quad_count == 1)
tcode = TCODE_WRITE_QUADLET_REQUEST;