NFS: Fix a race in __nfs_list_for_each_server()

commit 9c07b75 upstream. The struct nfs_server gets put on the cl_superblocks list before the server->super field has been initialised, in which case the call to nfs_sb_active() will Oops. Add a check to ensure that we skip such a list entry. Fixes: 3c9e502 ("NFS: Add a helper nfs_client_for_each_server()") Signed-off-by: Trond Myklebust <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
frank-w · Oct 10, 2023 · b5c3bc4 · b5c3bc4
1 parent f0ea421
commit b5c3bc4
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
@@ -445,7 +445,7 @@ static int __nfs_list_for_each_server(struct list_head *head,
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(server, head, client_link) {
-		if (!nfs_sb_active(server->super))
+		if (!(server->super && nfs_sb_active(server->super)))
 			continue;
 		rcu_read_unlock();
 		if (last)