ACK: [Lucid][CVE-2013-6382] xfs: underflow bug in xfs_attrlist_by_handle()

[Brad Figg]

On 01/09/2014 09:10 AM, Luis Henriques wrote:
> From: Dan Carpenter <dan.carpenter at oracle.com>
> 
> CVE-2013-6382
> 
> BugLink: http://bugs.launchpad.net/bugs/1256091
> 
> If we allocate less than sizeof(struct attrlist) then we end up
> corrupting memory or doing a ZERO_PTR_SIZE dereference.
> 
> This can only be triggered with CAP_SYS_ADMIN.
> 
> Reported-by: Nico Golde <nico at ngolde.de>
> Reported-by: Fabian Yamaguchi <fabs at goesec.de>
> Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
> Reviewed-by: Dave Chinner <dchinner at redhat.com>
> Signed-off-by: Ben Myers <bpm at sgi.com>
> (back ported from commit 31978b5cc66b8ba8a7e8eef60b12395d41b7b890)
> Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
> ---
>  fs/xfs/linux-2.6/xfs_ioctl.c   | 3 ++-
>  fs/xfs/linux-2.6/xfs_ioctl32.c | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/linux-2.6/xfs_ioctl.c b/fs/xfs/linux-2.6/xfs_ioctl.c
> index 942362f..5663351 100644
> --- a/fs/xfs/linux-2.6/xfs_ioctl.c
> +++ b/fs/xfs/linux-2.6/xfs_ioctl.c
> @@ -410,7 +410,8 @@ xfs_attrlist_by_handle(
>  		return -XFS_ERROR(EPERM);
>  	if (copy_from_user(&al_hreq, arg, sizeof(xfs_fsop_attrlist_handlereq_t)))
>  		return -XFS_ERROR(EFAULT);
> -	if (al_hreq.buflen > XATTR_LIST_MAX)
> +	if (al_hreq.buflen < sizeof(struct attrlist) ||
> +	    al_hreq.buflen > XATTR_LIST_MAX)
>  		return -XFS_ERROR(EINVAL);
>  
>  	/*
> diff --git a/fs/xfs/linux-2.6/xfs_ioctl32.c b/fs/xfs/linux-2.6/xfs_ioctl32.c
> index bad485a..e671047 100644
> --- a/fs/xfs/linux-2.6/xfs_ioctl32.c
> +++ b/fs/xfs/linux-2.6/xfs_ioctl32.c
> @@ -361,7 +361,8 @@ xfs_compat_attrlist_by_handle(
>  	if (copy_from_user(&al_hreq, arg,
>  			   sizeof(compat_xfs_fsop_attrlist_handlereq_t)))
>  		return -XFS_ERROR(EFAULT);
> -	if (al_hreq.buflen > XATTR_LIST_MAX)
> +	if (al_hreq.buflen < sizeof(struct attrlist) ||
> +	    al_hreq.buflen > XATTR_LIST_MAX)
>  		return -XFS_ERROR(EINVAL);
>  
>  	/*
> 


-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com