ALSA: firewire-tascam: Fix integer overflow in midi_port_work()

commit 9f65df9c589f249435255da37a5dd11f1bc86f4d upstream.

As snd_fw_async_midi_port.consume_bytes is unsigned int, and
NSEC_PER_SEC is 1000000000L, the second multiplication in

    port->consume_bytes * 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 port->consume_bytes <= 16777.

Fixes: 531f471834 ("ALSA: firewire-lib/firewire-tascam: localize async midi port")
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20210111130251.361335-3-geert+renesas@glider.be
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Geert Uytterhoeven 2021-01-11 14:02:51 +01:00 committed by Greg Kroah-Hartman
parent c0e1ac275f
commit 5b984e538b

View File

@ -209,7 +209,7 @@ static void midi_port_work(struct work_struct *work)
/* Set interval to next transaction. */
port->next_ktime = ktime_add_ns(ktime_get(),
port->consume_bytes * 8 * NSEC_PER_SEC / 31250);
port->consume_bytes * 8 * (NSEC_PER_SEC / 31250));
/* Start this transaction. */
port->idling = false;