linux-kernel - Re: [PATCH] block/rnbd: Ensure err is always initialized in process

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Date:   Tue, 18 Aug 2020 08:55:28 +0200
From:   Jinpu Wang <jinpu.wang@...ud.ionos.com>
To:     Nathan Chancellor <natechancellor@...il.com>
Cc:     Danil Kipnis <danil.kipnis@...ud.ionos.com>,
        Jens Axboe <axboe@...nel.dk>,
        Guoqing Jiang <guoqing.jiang@...ud.ionos.com>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        Brooke Basile <brookebasile@...il.com>
Subject: Re: [PATCH] block/rnbd: Ensure err is always initialized in process_rdma

On Tue, Aug 18, 2020 at 8:50 AM Nathan Chancellor
<natechancellor@...il.com> wrote:
>
> Clang warns:
>
> drivers/block/rnbd/rnbd-srv.c:150:6: warning: variable 'err' is used
> uninitialized whenever 'if' condition is true
> [-Wsometimes-uninitialized]
>         if (IS_ERR(bio)) {
>             ^~~~~~~~~~~
> drivers/block/rnbd/rnbd-srv.c:177:9: note: uninitialized use occurs here
>         return err;
>                ^~~
> drivers/block/rnbd/rnbd-srv.c:150:2: note: remove the 'if' if its
> condition is always false
>         if (IS_ERR(bio)) {
>         ^~~~~~~~~~~~~~~~~~
> drivers/block/rnbd/rnbd-srv.c:126:9: note: initialize the variable 'err'
> to silence this warning
>         int err;
>                ^
>                 = 0
> 1 warning generated.
>
> err is indeed uninitialized when this statement is taken. Ensure that it
> is assigned the error value of bio before jumping to the error handling
> label.
>
> Fixes: 735d77d4fd28 ("rnbd: remove rnbd_dev_submit_io")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1134
> Reported-by: Brooke Basile <brookebasile@...il.com>
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
Thanks!
Acked-by: Jack Wang <jinpu.wang@...ud.ionos.com>
> ---
>  drivers/block/rnbd/rnbd-srv.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/block/rnbd/rnbd-srv.c b/drivers/block/rnbd/rnbd-srv.c
> index 0fb94843a495..1b71cb2a885d 100644
> --- a/drivers/block/rnbd/rnbd-srv.c
> +++ b/drivers/block/rnbd/rnbd-srv.c
> @@ -148,7 +148,8 @@ static int process_rdma(struct rtrs_srv *sess,
>         /* Generate bio with pages pointing to the rdma buffer */
>         bio = rnbd_bio_map_kern(data, sess_dev->rnbd_dev->ibd_bio_set, datalen, GFP_KERNEL);
>         if (IS_ERR(bio)) {
> -               rnbd_srv_err(sess_dev, "Failed to generate bio, err: %ld\n", PTR_ERR(bio));
> +               err = PTR_ERR(bio);
> +               rnbd_srv_err(sess_dev, "Failed to generate bio, err: %ld\n", err);
>                 goto sess_dev_put;
>         }
>
> --
> 2.28.0
>