linux-kernel - Re: [PATCH 1/2] sysctl: add overflow detection to proc_get

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Date:   Mon, 15 Oct 2018 01:13:25 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     christian@...uner.io
Cc:     linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk
Subject: Re: [PATCH 1/2] sysctl: add overflow detection to proc_get_long()

> > Yecchh...  First of all, the cast back to unsigned long long is completely
> > pointless.  What's more,
> 
> Sorry, seriously asking: why?

In C everything is casted to the same type before doing an operation,
in this case comparison

> This was meant to handle the case where
> sizeof(unsigned long long) != sizeof(unsigned long) and I just looked at
> _kstrtoul() which does the same:

Second cast is unnecessary. I don't remember why I did 2 casts.