[CVE-2010-4529 Lucid] irda: prevent integer underflow in IRLMP_ENUMDEVICES, CVE-2010-4529

[Tim Gardner]

On 03/21/2011 02:17 PM, Leann Ogasawara wrote:
> The following changes since commit d524d2d15c73e43c3bbb0a2e63d8c8912aa0cb8f:
>    Leann Ogasawara (1):
>          igb: only use vlan_gro_receive if vlans are registered, CVE-2010-4263
>
> are available in the git repository at:
>
>    git://kernel.ubuntu.com/ogasawara/ubuntu-lucid.git CVE-2010-4529
>
> Dan Rosenberg (1):
>        irda: prevent integer underflow in IRLMP_ENUMDEVICES, CVE-2010-4529
>
>   net/irda/af_irda.c |   16 +++++++++-------
>   1 files changed, 9 insertions(+), 7 deletions(-)
>
>  From 569f2b303a56863f8fb98e57b64a7610d8c768b2 Mon Sep 17 00:00:00 2001
> From: Dan Rosenberg<drosenberg at vsecurity.com>
> Date: Wed, 22 Dec 2010 13:58:27 +0000
> Subject: [PATCH] irda: prevent integer underflow in IRLMP_ENUMDEVICES, CVE-2010-4529
>
> CVE-2010-4529
>
> BugLink: http://bugs.launchpad.net/bugs/737823
>
> If the user-provided len is less than the expected offset, the
> IRLMP_ENUMDEVICES getsockopt will do a copy_to_user() with a very large
> size value.  While this isn't be a security issue on x86 because it will
> get caught by the access_ok() check, it may leak large amounts of kernel
> heap on other architectures.  In any event, this patch fixes it.
>
> Signed-off-by: Dan Rosenberg<drosenberg at vsecurity.com>
> Signed-off-by: David S. Miller<davem at davemloft.net>
> (backport of upstream commit fdac1e0697356ac212259f2147aa60c72e334861)
>
> Signed-off-by: Leann Ogasawara<leann.ogasawara at canonical.com>
> ---
>   net/irda/af_irda.c |   16 +++++++++-------
>   1 files changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/net/irda/af_irda.c b/net/irda/af_irda.c
> index b6cef98..476b24e 100644
> --- a/net/irda/af_irda.c
> +++ b/net/irda/af_irda.c
> @@ -2164,6 +2164,14 @@ static int irda_getsockopt(struct socket *sock, int level, int optname,
>
>   	switch (optname) {
>   	case IRLMP_ENUMDEVICES:
> +
> +		/* Offset to first device entry */
> +		offset = sizeof(struct irda_device_list) -
> +			sizeof(struct irda_device_info);
> +
> +		if (len<  offset)
> +			return -EINVAL;
> +
>   		/* Ask lmp for the current discovery log */
>   		discoveries = irlmp_get_discoveries(&list.len, self->mask.word,
>   						    self->nslots);
> @@ -2173,15 +2181,9 @@ static int irda_getsockopt(struct socket *sock, int level, int optname,
>   		err = 0;
>
>   		/* Write total list length back to client */
> -		if (copy_to_user(optval,&list,
> -				 sizeof(struct irda_device_list) -
> -				 sizeof(struct irda_device_info)))
> +		if (copy_to_user(optval,&list, offset))
>   			err = -EFAULT;
>
> -		/* Offset to first device entry */
> -		offset = sizeof(struct irda_device_list) -
> -			sizeof(struct irda_device_info);
> -
>   		/* Copy the list itself - watch for overflow */
>   		if(list.len>  2048)
>   		{

Acked-by: Tim Gardner <tim.gardner at canonical.com>

-- 
Tim Gardner tim.gardner at canonical.com