ALSA: fireface: Fix integer overflow in transmit_midi_msg()

commit e7c22eeaff8565d9a8374f320238c251ca31480b upstream.

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 <[email protected]>
Signed-off-by: Geert Uytterhoeven <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
This commit is contained in:
Geert Uytterhoeven 2021-01-11 14:02:50 +01:00 • committed by Greg Kroah-Hartman
commit 68e67535e2

View file

@ -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;