From: Sean Young <sean@mess.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Mauro Carvalho Chehab" <mchehab@infradead.org>,
"Paul Gortmaker" <paul.gortmaker@windriver.com>,
"David Härdeman" <david@hardeman.nu>,
"Ben Hutchings" <ben@decadent.org.uk>,
linux-media@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [patch v2] [media] rc-core: prevent divide by zero bug in s_tx_carrier()
Date: Sun, 9 Sep 2012 23:26:30 +0100 [thread overview]
Message-ID: <20120909222629.GA28355@pequod.mess.org> (raw)
In-Reply-To: <20120909203142.GA12296@elgon.mountain>
On Sun, Sep 09, 2012 at 11:31:42PM +0300, Dan Carpenter wrote:
> Several of the drivers use carrier as a divisor in their s_tx_carrier()
> functions. We should do a sanity check here like we do for
> LIRC_SET_REC_CARRIER.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> v2: Ben Hutchings pointed out that my first patch was not a complete
> fix.
>
> diff --git a/drivers/media/rc/ir-lirc-codec.c b/drivers/media/rc/ir-lirc-codec.c
> index 6ad4a07..28dc0f0 100644
> --- a/drivers/media/rc/ir-lirc-codec.c
> +++ b/drivers/media/rc/ir-lirc-codec.c
> @@ -211,6 +211,9 @@ static long ir_lirc_ioctl(struct file *filep, unsigned int cmd,
> if (!dev->s_tx_carrier)
> return -EINVAL;
This should be ENOSYS.
>
> + if (val <= 0)
> + return -EINVAL;
> +
1) val is unsigned so it would never be less than zero.
2) A value of zero means disabling carrier modulation, which is used by
the mceusb driver.
So the check belongs in the individual drivers, as in the original patch.
Sean
next prev parent reply other threads:[~2012-09-09 22:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-09 20:31 [patch v2] [media] rc-core: prevent divide by zero bug in s_tx_carrier() Dan Carpenter
2012-09-09 21:01 ` walter harms
2012-09-09 22:00 ` Ben Hutchings
2012-09-09 22:26 ` Sean Young [this message]
2012-09-09 22:38 ` Ben Hutchings
2012-09-11 11:11 ` [patch v3] [media] rc: divide by zero bugs " Dan Carpenter
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