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

[Stefan Bader]

On 03/21/2011 08:17 PM, Leann Ogasawara wrote:
> The following changes since commit d57e49668c98881fc4daab39ea71dc24f838ea85:
>   Leann Ogasawara (1):
>         sound: Prevent buffer overflow in OSS load_mixer_volumes, CVE-2010-4527
> 
> are available in the git repository at:
> 
>   git://kernel.ubuntu.com/ogasawara/ubuntu-karmic.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 bbe20d84f2bc23756faf61ad1ca4e750b41d0e30 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 ad88268..a93afad 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: Stefan Bader <stefan.bader at canonical.com>