From: Dave Chinner <david@fromorbit.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Fabian Yamaguchi <fabs@goesec.de>,
security@kernel.org, Alex Elder <elder@kernel.org>,
xfs@oss.sgi.com, Ben Myers <bpm@sgi.com>,
Nico Golde <nico@ngolde.de>
Subject: Re: [patch] xfs: underflow bug in xfs_attrlist_by_handle()
Date: Fri, 1 Nov 2013 08:34:56 +1100 [thread overview]
Message-ID: <20131031213456.GM4446@dastard> (raw)
In-Reply-To: <20131031180010.GA24839@longonot.mountain>
On Thu, Oct 31, 2013 at 09:00:10PM +0300, Dan Carpenter wrote:
> 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@ngolde.de>
> Reported-by: Fabian Yamaguchi <fabs@goesec.de>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 4d61340..33ad9a7 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -442,7 +442,8 @@ 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);
Yup, that's not checked in xfs_attr_list(). Looks like these are the
only direct callers of xfs_attr_list(), and the other callers of
xfs_attr_list_int() don't appear to have the same issue. Good find!
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2013-10-31 21:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20131025144452.GA28451@ngolde.de>
2013-10-31 18:00 ` [patch] xfs: underflow bug in xfs_attrlist_by_handle() Dan Carpenter
2013-10-31 21:34 ` Dave Chinner [this message]
2013-12-04 21:53 ` Ben Myers
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