From f18e8774f4d3137fa0a5fb8ffa83d59a719666d8 Mon Sep 17 00:00:00 2001 From: Karl Mehltretter Date: Thu, 27 Aug 2026 14:42:54 +0100 Subject: [PATCH] netfs: Fix uninitialized return value in netfs_unbuffered_write() If preparation of the first subrequest fails, netfs_unbuffered_write() exits its loop before ret is initialized. The empty-iterator check can do the same. For synchronous writes, netfs_unbuffered_write_iter_locked() may then return an unrelated error instead of wreq->error. This is reachable through CIFS if cifs_prepare_write() fails to reopen the file or obtain credits. Initialize ret to 0 so the caller returns wreq->error if no data was written, or the number of bytes already written otherwise. Found with Clang's -Wconditional-uninitialized. Fixes: a0b4c7a49137e ("netfs: Fix unbuffered/DIO writes to dispatch subrequests in strict sequence") Cc: stable@vger.kernel.org Signed-off-by: Karl Mehltretter Signed-off-by: David Howells Link: https://patch.msgid.link/20260827134304.2075713-2-dhowells@redhat.com Acked-by: Paulo Alcantara Signed-off-by: Christian Brauner (Amutable) --- fs/netfs/direct_write.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c index c16fbad286a1..b04019097ab8 100644 --- a/fs/netfs/direct_write.c +++ b/fs/netfs/direct_write.c @@ -95,7 +95,7 @@ static int netfs_unbuffered_write(struct netfs_io_request *wreq) { struct netfs_io_subrequest *subreq = NULL; struct netfs_io_stream *stream = &wreq->io_streams[0]; - int ret; + int ret = 0; _enter("%llx", wreq->len);