linux-kernel - [PATCH] ksmbd: Fix to handle removal of rfc1002 header from smb

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Message-ID: <712257.1766069339@warthog.procyon.org.uk>
Date: Thu, 18 Dec 2025 14:48:59 +0000
From: David Howells <dhowells@...hat.com>
To: Namjae Jeon <linkinjeon@...nel.org>,
    Steve French <sfrench@...ba.org>
cc: dhowells@...hat.com, Sergey Senozhatsky <senozhatsky@...omium.org>,
    Tom Talpey <tom@...pey.com>, Paulo Alcantara <pc@...guebit.org>,
    Shyam Prasad N <sprasad@...rosoft.com>, linux-cifs@...r.kernel.org,
    netfs@...ts.linux.dev, linux-fsdevel@...r.kernel.org,
    linux-kernel@...r.kernel.org
Subject: [PATCH] ksmbd: Fix to handle removal of rfc1002 header from smb_hdr

Hi Namjae,

Does this (untested) patch fix the problem for you?

David
---
The commit that removed the RFC1002 header from struct smb_hdr didn't also
fix the places in ksmbd that use it in order to provide graceful rejection
of SMB1 protocol requests.

Fixes: 83bfbd0bb902 ("cifs: Remove the RFC1002 header from smb_hdr")
Reported-by: Namjae Jeon <linkinjeon@...nel.org>
Link: https://lore.kernel.org/r/CAKYAXd9Ju4MFkkH5Jxfi1mO0AWEr=R35M3vQ_Xa7Yw34JoNZ0A@mail.gmail.com/
Signed-off-by: David Howells <dhowells@...hat.com>
cc: Steve French <sfrench@...ba.org>
cc: Sergey Senozhatsky <senozhatsky@...omium.org>
cc: Tom Talpey <tom@...pey.com>
cc: Paulo Alcantara <pc@...guebit.org>
cc: Shyam Prasad N <sprasad@...rosoft.com>
cc: linux-cifs@...r.kernel.org
cc: netfs@...ts.linux.dev
cc: linux-fsdevel@...r.kernel.org
---
 fs/smb/server/server.c     |    2 +-
 fs/smb/server/smb_common.c |   10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c
index 3cea16050e4f..bedc8390b6db 100644
--- a/fs/smb/server/server.c
+++ b/fs/smb/server/server.c
@@ -95,7 +95,7 @@ static inline int check_conn_state(struct ksmbd_work *work)
 
 	if (ksmbd_conn_exiting(work->conn) ||
 	    ksmbd_conn_need_reconnect(work->conn)) {
-		rsp_hdr = work->response_buf;
+		rsp_hdr = smb2_get_msg(work->response_buf);
 		rsp_hdr->Status.CifsError = STATUS_CONNECTION_DISCONNECTED;
 		return 1;
 	}
diff --git a/fs/smb/server/smb_common.c b/fs/smb/server/smb_common.c
index b23203a1c286..d6084580b59d 100644
--- a/fs/smb/server/smb_common.c
+++ b/fs/smb/server/smb_common.c
@@ -140,7 +140,7 @@ int ksmbd_verify_smb_message(struct ksmbd_work *work)
 	if (smb2_hdr->ProtocolId == SMB2_PROTO_NUMBER)
 		return ksmbd_smb2_check_message(work);
 
-	hdr = work->request_buf;
+	hdr = smb2_get_msg(work->request_buf);
 	if (*(__le32 *)hdr->Protocol == SMB1_PROTO_NUMBER &&
 	    hdr->Command == SMB_COM_NEGOTIATE) {
 		work->conn->outstanding_credits++;
@@ -278,7 +278,6 @@ static int ksmbd_negotiate_smb_dialect(void *buf)
 						  req->DialectCount);
 	}
 
-	proto = *(__le32 *)((struct smb_hdr *)buf)->Protocol;
 	if (proto == SMB1_PROTO_NUMBER) {
 		struct smb_negotiate_req *req;
 
@@ -320,8 +319,8 @@ static u16 get_smb1_cmd_val(struct ksmbd_work *work)
  */
 static int init_smb1_rsp_hdr(struct ksmbd_work *work)
 {
-	struct smb_hdr *rsp_hdr = (struct smb_hdr *)work->response_buf;
-	struct smb_hdr *rcv_hdr = (struct smb_hdr *)work->request_buf;
+	struct smb_hdr *rsp_hdr = (struct smb_hdr *)smb2_get_msg(work->response_buf);
+	struct smb_hdr *rcv_hdr = (struct smb_hdr *)smb2_get_msg(work->request_buf);
 
 	rsp_hdr->Command = SMB_COM_NEGOTIATE;
 	*(__le32 *)rsp_hdr->Protocol = SMB1_PROTO_NUMBER;
@@ -412,9 +411,10 @@ static int init_smb1_server(struct ksmbd_conn *conn)
 
 int ksmbd_init_smb_server(struct ksmbd_conn *conn)
 {
+	struct smb_hdr *rcv_hdr = (struct smb_hdr *)smb2_get_msg(conn->request_buf);
 	__le32 proto;
 
-	proto = *(__le32 *)((struct smb_hdr *)conn->request_buf)->Protocol;
+	proto = *(__le32 *)rcv_hdr->Protocol;
 	if (conn->need_neg == false) {
 		if (proto == SMB1_PROTO_NUMBER)
 			return -EINVAL;