linux-kernel - Re: [PATCH 0/3] cast sizeof to int for comparison

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Message-ID: <alpine.DEB.2.20.1807012050530.2494@hadrien>
Date:   Sun, 1 Jul 2018 20:51:55 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     Joe Perches <joe@...ches.com>
cc:     linux-usb@...r.kernel.org, Chengguang Xu <cgxu519@....com>,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-input@...r.kernel.org, linux-media@...r.kernel.org
Subject: Re: [PATCH 0/3] cast sizeof to int for comparison



On Sun, 1 Jul 2018, Joe Perches wrote:

> On Sun, 2018-07-01 at 19:32 +0200, Julia Lawall wrote:
> > Comparing an int to a size, which is unsigned, causes the int to become
> > unsigned, giving the wrong result.
> >
> > The semantic match that finds this problem is as follows:
> > (http://coccinelle.lip6.fr/)
>
> Great, thanks.
>
> But what about the ones in net/smc like:
>
> > net/smc/smc_clc.c:
> >
> >         len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1,
> >                              sizeof(struct smc_clc_msg_decline));
> >         if (len < sizeof(struct smc_clc_msg_decline))
>
> Are those detected by the semantic match and ignored?

I wasn't sure how to justify that kernel_sendmsg returns a negative value.
If it is the case, I can send the patch.  I only found this in one file,
but there were multiple occurrences.

julia