9p: acl: fix uninitialized iattr access

iattr is passed to v9fs_vfs_setattr_dotl which does send various
values from iattr over the wire, even if it tells the server to
only look at iattr.ia_valid fields this could leak some stack data.

Link: http://lkml.kernel.org/r/1536339057-21974-2-git-send-email-asmadeus@codewreck.org
Addresses-Coverity-ID: 1195601 ("Uninitalized scalar variable")
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>

fs/9p/acl.c

@@ -276,7 +276,7 @@ static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
 	switch (handler->flags) {
 	case ACL_TYPE_ACCESS:
 		if (acl) {
-			struct iattr iattr;
+			struct iattr iattr = { 0 };
 			struct posix_acl *old_acl = acl;
 
 			retval = posix_acl_update_mode(inode, &iattr.ia_mode, &acl);