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@ngolde.de>
Reported-by: Fabian Yamaguchi <fabs@goesec.de>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
(cherry picked from commit 071c529eb672648ee8ca3f90944bcbcc730b4c06)
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index d99a905189091c9b74fa23f6483d8a2713ae7c4a..eb519de680475dc898c6869c89caca5b92bdae41 100644 (file)
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -404,7 +404,8 @@ 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 54e623bfbb85e9642b7556926aea25e71fed519b..0d685b3fb609d9242d5b40cc098a27621b0b5633 100644 (file)
--- a/fs/xfs/xfs_ioctl32.c
+++ b/fs/xfs/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);
 
        /*