[3.8.y.z extended stable] Patch "xfs: underflow bug in xfs_attrlist_by_handle()" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    xfs: underflow bug in xfs_attrlist_by_handle()

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.19.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From a813ba6f997483565d92b7cb633e7e809a68b8b6 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter at oracle.com>
Date: Thu, 31 Oct 2013 21:00:10 +0300
Subject: xfs: underflow bug in xfs_attrlist_by_handle()

commit 31978b5cc66b8ba8a7e8eef60b12395d41b7b890 upstream.

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>

(cherry picked from commit 071c529eb672648ee8ca3f90944bcbcc730b4c06)
[ kamal: 3.8-stable for CVE-2013-6382 ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/xfs/xfs_ioctl.c   | 3 ++-
 fs/xfs/xfs_ioctl32.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 2fe3eb3..cdaef2d 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -409,7 +409,8 @@ 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/xfs_ioctl32.c b/fs/xfs/xfs_ioctl32.c
index 1244274..b8bfe2a 100644
--- a/fs/xfs/xfs_ioctl32.c
+++ b/fs/xfs/xfs_ioctl32.c
@@ -359,7 +359,8 @@ 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);

 	/*
--
1.8.3.2