[PATCH 4.4 138/192] [PATCH 4.4 08/16] cred: Reject inodes with invalid ids in set_create_file_as()

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Seth Forshee <seth.fors...@canonical.com>

[ Upstream commit 5f65e5ca286126a60f62c8421b77c2018a482b8a ]

Using INVALID_[UG]ID for the LSM file creation context doesn't
make sense, so return an error if the inode passed to
set_create_file_as() has an invalid id.

Signed-off-by: Seth Forshee <seth.fors...@canonical.com>
Acked-by: Serge Hallyn <serge.hal...@canonical.com>
Signed-off-by: Eric W. Biederman <ebied...@xmission.com>
Signed-off-by: Sasha Levin <alexander.le...@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 kernel/cred.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -689,6 +689,8 @@ EXPORT_SYMBOL(set_security_override_from
  */
 int set_create_files_as(struct cred *new, struct inode *inode)
 {
+       if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid))
+               return -EINVAL;
        new->fsuid = inode->i_uid;
        new->fsgid = inode->i_gid;
        return security_kernel_create_files_as(new, inode);