linux-hardening - RE: [PATCH] mac80211: Recast pointer for trailing memcpy()

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Message-ID: <1bd7df33fd484d1da656238f792bd6f7@AcuMS.aculab.com>
Date:   Fri, 18 Jun 2021 08:42:16 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Kees Cook' <keescook@...omium.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Johannes Berg <johannes@...solutions.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org>
Subject: RE: [PATCH] mac80211: Recast pointer for trailing memcpy()

From: Kees Cook
> Sent: 17 June 2021 05:27
> 
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memcpy(), memmove(), and memset(), avoid
> intentionally writing across neighboring array fields.
> 
> Give memcpy() a specific source pointer type so it can correctly
> calculate the bounds of the copy.

Doesn't the necessity of this sort of patch just sidestep the
run-time checking and really indicate that it is just a complete
waste of cpu resources?

I bet code changes to avoid/fix the reported errors will
introduce more bugs than the test itself will really find.

	David

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