Re: [PATCH net-next] net/smc: cast sizeof to int for comparison

[Ursula Braun]

On 09/15/2018 12:00 PM, YueHaibing wrote:
> Comparing an int to a size, which is unsigned, causes the int to become
> unsigned, giving the wrong result. kernel_sendmsg can return a negative
> error code.
> 

Thanks for reporting this issue!

> Signed-off-by: YueHaibing <yuehaib...@huawei.com>
> ---
>  net/smc/smc_clc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
> index 83aba9a..fd0f5ce 100644
> --- a/net/smc/smc_clc.c
> +++ b/net/smc/smc_clc.c
> @@ -446,7 +446,7 @@ int smc_clc_send_proposal(struct smc_sock *smc, int 
> smc_type,
>       vec[i++].iov_len = sizeof(trl);
>       /* due to the few bytes needed for clc-handshake this cannot block */
>       len = kernel_sendmsg(smc->clcsock, &msg, vec, i, plen);
> -     if (len < sizeof(pclc)) {
> +     if (len < (int)sizeof(pclc)) {
>               if (len >= 0) {
>                       reason_code = -ENETUNREACH;
>                       smc->sk.sk_err = -reason_code;
> 

Your fix helps, but I would like to follow the hint of Andreas Schwab, and split
the return value check like this:

---
 net/smc/smc_clc.c |   14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

--- a/net/smc/smc_clc.c
+++ b/net/smc/smc_clc.c
@@ -446,14 +446,12 @@ int smc_clc_send_proposal(struct smc_soc
        vec[i++].iov_len = sizeof(trl);
        /* due to the few bytes needed for clc-handshake this cannot block */
        len = kernel_sendmsg(smc->clcsock, &msg, vec, i, plen);
-       if (len < sizeof(pclc)) {
-               if (len >= 0) {
-                       reason_code = -ENETUNREACH;
-                       smc->sk.sk_err = -reason_code;
-               } else {
-                       smc->sk.sk_err = smc->clcsock->sk->sk_err;
-                       reason_code = -smc->sk.sk_err;
-               }
+       if (len < 0) {
+               smc->sk.sk_err = smc->clcsock->sk->sk_err;
+               reason_code = -smc->sk.sk_err;
+       } else if (len < (int)sizeof(pclc)) {
+               reason_code = -ENETUNREACH;
+               smc->sk.sk_err = -reason_code;
        }
 
        return reason_code;

Agreed?

Regards, Ursula