linux-kernel - [PATCH] cifs: set length when cifs_copy_pages_to

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Message-Id: <20220526140226.2648689-1-trix@redhat.com>
Date:   Thu, 26 May 2022 10:02:26 -0400
From:   Tom Rix <trix@...hat.com>
To:     sfrench@...ba.org, nathan@...nel.org, ndesaulniers@...gle.com,
        dhowells@...hat.com
Cc:     linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        Tom Rix <trix@...hat.com>
Subject: [PATCH] cifs: set length when cifs_copy_pages_to_iter is successful

clang build fails with
fs/cifs/smb2ops.c:4984:7: error: variable 'length' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
  if (rdata->result != 0) {
      ^~~~~~~~~~~~~~~~~~

handle_read_data() returns the number of bytes handled by setting the length variable.
This only happens in the copy_to_iter() branch, it needs to also happen in the
cifs_copy_pages_to_iter() branch.  When cifs_copy_pages_to_iter() is successful,
its parameter data_len is how many bytes were handled, so set length to data_len.

Fixes: 67fd8cff2b0f ("cifs: Change the I/O paths to use an iterator rather than a page list")
Signed-off-by: Tom Rix <trix@...hat.com>
---
 fs/cifs/smb2ops.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 3630e132781f..bfad482ec186 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -4988,7 +4988,7 @@ handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid,
 				dequeue_mid(mid, rdata->result);
 			return 0;
 		}
-		rdata->got_bytes = pages_len;
+		length = rdata->got_bytes = pages_len;
 
 	} else if (buf_len >= data_offset + data_len) {
 		/* read response payload is in buf */
-- 
2.27.0