Re: [PATCH v2] nvme-tcp: fix signedness bug in nvme_tcp_init_connection()

[Caleb Sander Mateos]

On Wed, Mar 5, 2025 at 7:53 AM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> The kernel_recvmsg() function returns an int which could be either
> negative error codes or the number of bytes received.  The problem is
> that the condition:
>
>         if (ret < sizeof(*icresp)) {
>
> is type promoted to type unsigned long and negative values are treated
> as high positive values which is success, when they should be treated as
> failure.  Handle invalid positive returns separately from negative
> error codes to avoid this problem.
>
> Fixes: 578539e09690 ("nvme-tcp: fix connect failure on receiving partial ICResp PDU")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Reviewed-by: Caleb Sander Mateos <csander@xxxxxxxxxxxxxxx>
> Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
> Reviewed-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
> ---
> v2: Change the style.  Add the Reviewed-by tags.  (I will feel really bad
>     if I introduced a bug in between v1 and v2 and cause everyone
>     embarrassment with the R-b tags.)

Still looks good to me.
Reviewed-by: Caleb Sander Mateos <csander@xxxxxxxxxxxxxxx>

>
>  drivers/nvme/host/tcp.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> index 8a9131c95a3d..b23ce31df97d 100644
> --- a/drivers/nvme/host/tcp.c
> +++ b/drivers/nvme/host/tcp.c
> @@ -1495,11 +1495,11 @@ static int nvme_tcp_init_connection(struct nvme_tcp_queue *queue)
>         msg.msg_flags = MSG_WAITALL;
>         ret = kernel_recvmsg(queue->sock, &msg, &iov, 1,
>                         iov.iov_len, msg.msg_flags);
> -       if (ret < sizeof(*icresp)) {
> +       if (ret >= 0 && ret < sizeof(*icresp))
> +               ret = -ECONNRESET;
> +       if (ret < 0) {
>                 pr_warn("queue %d: failed to receive icresp, error %d\n",
>                         nvme_tcp_queue_id(queue), ret);

This log line is slightly less informative now if a partial PDU is
received, since it will log -ECONNRESET instead of the number of bytes
received before the connection was closed. But I think that's fine.

Best,
Caleb

> -               if (ret >= 0)
> -                       ret = -ECONNRESET;
>                 goto free_icresp;
>         }
>         ret = -ENOTCONN;
> --
> 2.47.2
>