1 files changed, 19 insertions, 0 deletions

diff --git a/fs/attr.c b/fs/attr.c
index 25b24d0f6c88..42bb42bb3c72 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -255,6 +255,25 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de
         if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
                 return 0;
 
+        /*
+         * Verify that uid/gid changes are valid in the target
+         * namespace of the superblock.
+         */
+        if (ia_valid & ATTR_UID &&
+            !kuid_has_mapping(inode->i_sb->s_user_ns, attr->ia_uid))
+                return -EOVERFLOW;
+        if (ia_valid & ATTR_GID &&
+            !kgid_has_mapping(inode->i_sb->s_user_ns, attr->ia_gid))
+                return -EOVERFLOW;
+
+        /* Don't allow modifications of files with invalid uids or
+         * gids unless those uids & gids are being made valid.
+         */
+        if (!(ia_valid & ATTR_UID) && !uid_valid(inode->i_uid))
+                return -EOVERFLOW;
+        if (!(ia_valid & ATTR_GID) && !gid_valid(inode->i_gid))
+                return -EOVERFLOW;
+
         error = security_inode_setattr(dentry, attr);
         if (error)
                 return error;