Re: [PATCH] ksmbd: Fix to handle removal of rfc1002 header from smb_hdr

[ChenXiaoSong]

Hi David,

Since the size of `struct smb_hdr` has changed, the value of 
`SMB1_MIN_SUPPORTED_HEADER_SIZE` should also be updated to 
`(sizeof(struct smb_hdr) + 4)`. `SMB1_MIN_SUPPORTED_HEADER_SIZE` is used 
in `ksmbd_conn_handler_loop()`.

Thanks,
ChenXiaoSong.

On 12/18/25 11:09 PM, ChenXiaoSong wrote:
> `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@xxxxxxxxxx>
> > Link: https://lore.kernel.org/r/ 
> > CAKYAXd9Ju4MFkkH5Jxfi1mO0AWEr=R35M3vQ_Xa7Yw34JoNZ0A@xxxxxxxxxxxxxx/
> > Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> > cc: Steve French <sfrench@xxxxxxxxx>
> > cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
> > cc: Tom Talpey <tom@xxxxxxxxxx>
> > cc: Paulo Alcantara <pc@xxxxxxxxxxxxx>
> > cc: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
> > cc: linux-cifs@xxxxxxxxxxxxxxx
> > cc: netfs@xxxxxxxxxxxxxxx
> > cc: linux-fsdevel@xxxxxxxxxxxxxxx
> > ---
> >   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;