From: Takashi Iwai <tiwai@suse.de>
To: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: alsa-devel@alsa-project.org, Takashi Iwai <tiwai@suse.com>,
Clemens Ladisch <clemens@ladisch.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH/RFC 2/2] ALSA: firewire-tascam: Fix integer overflow in midi_port_work()
Date: Tue, 12 Jan 2021 14:58:47 +0100 [thread overview]
Message-ID: <s5hsg76qmso.wl-tiwai@suse.de> (raw)
In-Reply-To: <20210111130251.361335-3-geert+renesas@glider.be>
On Mon, 11 Jan 2021 14:02:51 +0100,
Geert Uytterhoeven wrote:
>
> 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: 531f471834227d03 ("ALSA: firewire-lib/firewire-tascam: localize async midi port")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> Compile-tested only.
>
> I don't know the maximum transfer length of MIDI, but given it's an old
> standard, I guess it's rather small. If it is larger than 16777, the
> constant "8" should be replaced by "8ULL", to force 64-bit arithmetic.
Applied now. Thanks.
Takashi
prev parent reply other threads:[~2021-01-12 14:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-11 13:02 [PATCH/RFC 0/2] ALSA: firewire: Fix integer overflows on 32-bit Geert Uytterhoeven
2021-01-11 13:02 ` [PATCH/RFC 1/2] ALSA: fireface: Fix integer overflow in transmit_midi_msg() Geert Uytterhoeven
2021-01-12 13:53 ` Takashi Sakamoto
2021-01-12 13:58 ` Takashi Iwai
2021-01-11 13:02 ` [PATCH/RFC 2/2] ALSA: firewire-tascam: Fix integer overflow in midi_port_work() Geert Uytterhoeven
2021-01-12 13:42 ` Takashi Sakamoto
2021-01-12 13:55 ` Geert Uytterhoeven
2021-01-12 13:58 ` Takashi Iwai [this message]
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