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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index ca01d83..83dfe6e 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -409,7 +409,8 @@
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);
/*