Alsa-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Geert Uytterhoeven <geert+renesas@glider.be>
To: Clemens Ladisch <clemens@ladisch.de>,
	Takashi Sakamoto <o-takashi@sakamocchi.jp>,
	Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>
Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org,
	Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH/RFC 2/2] ALSA: firewire-tascam: Fix integer overflow in midi_port_work()
Date: Mon, 11 Jan 2021 14:02:51 +0100
Message-ID: <20210111130251.361335-3-geert+renesas@glider.be> (raw)
In-Reply-To: <20210111130251.361335-1-geert+renesas@glider.be>

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.
---
 sound/firewire/tascam/tascam-transaction.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/firewire/tascam/tascam-transaction.c b/sound/firewire/tascam/tascam-transaction.c
index 90288b4b46379526..a073cece4a7d5e3a 100644
--- a/sound/firewire/tascam/tascam-transaction.c
+++ b/sound/firewire/tascam/tascam-transaction.c
@@ -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;
-- 
2.25.1


  parent reply index

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 ` Geert Uytterhoeven [this message]
2021-01-12 13:42   ` [PATCH/RFC 2/2] ALSA: firewire-tascam: Fix integer overflow in midi_port_work() Takashi Sakamoto
2021-01-12 13:55     ` Geert Uytterhoeven
2021-01-12 13:58   ` Takashi Iwai

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210111130251.361335-3-geert+renesas@glider.be \
    --to=geert+renesas@glider.be \
    --cc=alsa-devel@alsa-project.org \
    --cc=clemens@ladisch.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=o-takashi@sakamocchi.jp \
    --cc=perex@perex.cz \
    --cc=tiwai@suse.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Alsa-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/alsa-devel/0 alsa-devel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 alsa-devel alsa-devel/ https://lore.kernel.org/alsa-devel \
		alsa-devel@alsa-project.org
	public-inbox-index alsa-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.alsa-project.alsa-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git