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

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Message-ID: <b5ebd3be-c567-44bb-9411-add5e79234dc@linux.dev>
Date: Thu, 18 Dec 2025 23:09:32 +0800
From: ChenXiaoSong <chenxiaosong.chenxiaosong@...ux.dev>
To: David Howells <dhowells@...hat.com>, Namjae Jeon <linkinjeon@...nel.org>,
 Steve French <sfrench@...ba.org>
Cc: 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: Re: [PATCH] ksmbd: Fix to handle removal of rfc1002 header from
 smb_hdr

`ksmbd_conn_handler_loop()` calls `get_rfc1002_len()`. Does this need to 
be updated as well?

Thanks,
ChenXiaoSong.

On 12/18/25 10:48 PM, David Howells wrote:
> 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;
> 
>