Re: [PATCH v4 07/11] cifs: Clean up some places where an extra kvec[] was required for rfc1002

Stefan Metzmacher
2025-11-24T14:20:13Z

Hi David,

I had to squash this into the patch

I'm using smatch when building and got the following error
with this change:

client/transport.c:1073 compound_send_recv() error: we previously assumed 'resp_iov' could be null (see line 1051)

See my inline comment below to see where the problem is introduced.

It goes away when I squash the following:

diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c
index c023c9873c88..7036acd6542b 100644
--- a/fs/smb/client/transport.c
+++ b/fs/smb/client/transport.c
@@ -995,6 +995,9 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
if ((ses->ses_status == SES_NEW) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
spin_unlock(&ses->ses_lock);

+ if (WARN_ON_ONCE(num_rqst != 1 || !resp_iov))
+ return -EINVAL;
+
cifs_server_lock(server);
smb311_update_preauth_hash(ses, server, rqst[0].rq_iov, rqst[0].rq_nvec);
cifs_server_unlock(server);

Am 24.11.25 um 13:42 schrieb David Howells:
> Clean up some places where previously an extra element in the kvec array
> was being used to hold an rfc1002 header for SMB1 (a previous patch removed
> this and generated it on the fly as for SMB2/3).
>
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: Steve French <sfrench@samba.org>
> cc: Paulo Alcantara <pc@manguebit.org>
> cc: Shyam Prasad N <sprasad@microsoft.com>
> cc: Tom Talpey <tom@talpey.com>
> cc: linux-cifs@vger.kernel.org
> cc: netfs@lists.linux.dev
> cc: linux-fsdevel@vger.kernel.org
> ---
> fs/smb/client/cifsencrypt.c | 52 ++++++++---------------------------
> fs/smb/client/cifsproto.h | 5 ----
> fs/smb/client/cifstransport.c | 20 ++------------
> fs/smb/client/smb1ops.c | 12 +++++---
> fs/smb/client/transport.c | 25 +++++++++--------
> 5 files changed, 35 insertions(+), 79 deletions(-)
>
> diff --git a/fs/smb/client/cifsencrypt.c b/fs/smb/client/cifsencrypt.c
> index 1e0ac87c6686..a9a57904c6b1 100644
> --- a/fs/smb/client/cifsencrypt.c
> +++ b/fs/smb/client/cifsencrypt.c
> @@ -86,26 +86,21 @@ static int cifs_sig_iter(const struct iov_iter *iter, size_t maxsize,
> int __cifs_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server,
> char *signature, struct cifs_calc_sig_ctx *ctx)
> {
> - int i;
> + struct iov_iter iter;
> ssize_t rc;
> - struct kvec *iov = rqst->rq_iov;
> - int n_vec = rqst->rq_nvec;
> + size_t size = 0;
>
> - for (i = 0; i < n_vec; i++) {
> - if (iov[i].iov_len == 0)
> - continue;
> - if (iov[i].iov_base == NULL) {
> - cifs_dbg(VFS, "null iovec entry\n");
> - return -EIO;
> - }
> + for (int i = 0; i < rqst->rq_nvec; i++)
> + size += rqst->rq_iov[i].iov_len;
>
> - rc = cifs_sig_update(ctx, iov[i].iov_base, iov[i].iov_len);
> - if (rc) {
> - cifs_dbg(VFS, "%s: Could not update with payload\n",
> - __func__);
> - return rc;
> - }
> - }
> + iov_iter_kvec(&iter, ITER_SOURCE, rqst->rq_iov, rqst->rq_nvec, size);
> +
> + if (iov_iter_count(&iter) <= 4)
> + return -EIO;
> +
> + rc = cifs_sig_iter(&iter, iov_iter_count(&iter), ctx);
> + if (rc < 0)
> + return rc;
>
> rc = cifs_sig_iter(&rqst->rq_iter, iov_iter_count(&rqst->rq_iter), ctx);
> if (rc < 0)
> @@ -186,29 +181,6 @@ int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server,
> return rc;
> }
>
> -int cifs_sign_smbv(struct kvec *iov, int n_vec, struct TCP_Server_Info *server,
> - __u32 *pexpected_response_sequence)
> -{
> - struct smb_rqst rqst = { .rq_iov = iov,
> - .rq_nvec = n_vec };
> -
> - return cifs_sign_rqst(&rqst, server, pexpected_response_sequence);
> -}
> -
> -/* must be called with server->srv_mutex held */
> -int cifs_sign_smb(struct smb_hdr *cifs_pdu, unsigned int pdu_len,
> - struct TCP_Server_Info *server,
> - __u32 *pexpected_response_sequence_number)
> -{
> - struct kvec iov[1] = {
> - [0].iov_base = (char *)cifs_pdu,
> - [0].iov_len = pdu_len,
> - };
> -
> - return cifs_sign_smbv(iov, ARRAY_SIZE(iov), server,
> - pexpected_response_sequence_number);
> -}
> -
> int cifs_verify_signature(struct smb_rqst *rqst,
> struct TCP_Server_Info *server,
> __u32 expected_sequence_number)
> diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
> index 4af6ea8150c3..39586f2dfad5 100644
> --- a/fs/smb/client/cifsproto.h
> +++ b/fs/smb/client/cifsproto.h
> @@ -68,11 +68,6 @@ int __cifs_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server,
> char *signature, struct cifs_calc_sig_ctx *ctx);
> int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server,
> __u32 *pexpected_response_sequence_number);
> -int cifs_sign_smbv(struct kvec *iov, int n_vec, struct TCP_Server_Info *server,
> - __u32 *pexpected_response_sequence);
> -int cifs_sign_smb(struct smb_hdr *cifs_pdu, unsigned int pdu_len,
> - struct TCP_Server_Info *server,
> - __u32 *pexpected_response_sequence_number);
> int cifs_verify_signature(struct smb_rqst *rqst,
> struct TCP_Server_Info *server,
> __u32 expected_sequence_number);
> diff --git a/fs/smb/client/cifstransport.c b/fs/smb/client/cifstransport.c
> index 1a0b80fc97d4..6fa60de786e9 100644
> --- a/fs/smb/client/cifstransport.c
> +++ b/fs/smb/client/cifstransport.c
> @@ -71,22 +71,6 @@ alloc_mid(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
> return smb;
> }
>
> -int
> -smb_send(struct TCP_Server_Info *server, struct smb_hdr *smb_buffer,
> - unsigned int smb_buf_length)
> -{
> - struct kvec iov[1] = {
> - [0].iov_base = smb_buffer,
> - [0].iov_len = smb_buf_length,
> - };
> - struct smb_rqst rqst = {
> - .rq_iov = iov,
> - .rq_nvec = ARRAY_SIZE(iov),
> - };
> -
> - return __smb_send_rqst(server, 1, &rqst);
> -}
> -
> static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
> struct smb_message **ppmidQ)
> {
> @@ -370,7 +354,7 @@ int SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
> return rc;
> }
>
> - rc = cifs_sign_smb(in_buf, in_len, server, &smb->sequence_number);
> + rc = cifs_sign_rqst(&rqst, server, &smb->sequence_number);
> if (rc) {
> delete_mid(smb);
> cifs_server_unlock(server);
> @@ -378,7 +362,7 @@ int SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
> }
>
> smb->mid_state = MID_REQUEST_SUBMITTED;
> - rc = smb_send(server, in_buf, in_len);
> + rc = __smb_send_rqst(server, 1, &rqst);
> cifs_save_when_sent(smb);
>
> if (rc < 0)
> diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
> index 91205685057c..6b0d0b511b9f 100644
> --- a/fs/smb/client/smb1ops.c
> +++ b/fs/smb/client/smb1ops.c
> @@ -34,17 +34,21 @@ static int
> send_nt_cancel(struct TCP_Server_Info *server, struct smb_rqst *rqst,
> struct smb_message *smb)
> {
> - int rc = 0;
> struct smb_hdr *in_buf = (struct smb_hdr *)rqst->rq_iov[0].iov_base;
> - unsigned int in_len = rqst->rq_iov[0].iov_len;
> + struct kvec iov[1];
> + struct smb_rqst crqst = { .rq_iov = iov, .rq_nvec = 1 };
> + int rc = 0;
>
> /* +2 for BCC field */
> in_buf->Command = SMB_COM_NT_CANCEL;
> in_buf->WordCount = 0;
> put_bcc(0, in_buf);
>
> + iov[0].iov_base = in_buf;
> + iov[0].iov_len = sizeof(struct smb_hdr) + 2;
> +
> cifs_server_lock(server);
> - rc = cifs_sign_smb(in_buf, in_len, server, &smb->sequence_number);
> + rc = cifs_sign_rqst(&crqst, server, &smb->sequence_number);
> if (rc) {
> cifs_server_unlock(server);
> return rc;
> @@ -56,7 +60,7 @@ send_nt_cancel(struct TCP_Server_Info *server, struct smb_rqst *rqst,
> * after signing here.
> */
> --server->sequence_number;
> - rc = smb_send(server, in_buf, in_len);
> + rc = __smb_send_rqst(server, 1, &crqst);
> if (rc < 0)
> server->sequence_number--;
>
> diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c
> index 2e338e186809..c023c9873c88 100644
> --- a/fs/smb/client/transport.c
> +++ b/fs/smb/client/transport.c
> @@ -1043,22 +1043,23 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
> goto out;
> }
>
> - buf = (char *)smb[i]->resp_buf;
> - resp_iov[i].iov_base = buf;
> - resp_iov[i].iov_len = smb[i]->resp_buf_size;
> -
> - if (smb[i]->large_buf)
> - resp_buf_type[i] = CIFS_LARGE_BUFFER;
> - else
> - resp_buf_type[i] = CIFS_SMALL_BUFFER;
> -
> rc = server->ops->check_receive(smb[i], server,
> flags & CIFS_LOG_ERROR);
>
> - /* mark it so buf will not be freed by delete_mid */
> - if ((flags & CIFS_NO_RSP_BUF) == 0)
> - smb[i]->resp_buf = NULL;
> + if (resp_iov) {

Is it really possible that resp_iov is NULL here?

I guess it is for things with CIFS_NO_RSP_BUF, correct?

> + buf = (char *)smb[i]->resp_buf;
> + resp_iov[i].iov_base = buf;
> + resp_iov[i].iov_len = smb[i]->resp_buf_size;
>
> + if (smb[i]->large_buf)
> + resp_buf_type[i] = CIFS_LARGE_BUFFER;
> + else
> + resp_buf_type[i] = CIFS_SMALL_BUFFER;
> +
> + /* mark it so buf will not be freed by delete_mid */
> + if ((flags & CIFS_NO_RSP_BUF) == 0)
> + smb[i]->resp_buf = NULL;
> + }
> }
>
> /*
>