linux-kernel - Re: [lkp-robot] [include/linux/string.h] 6974f0c455: kernel_BUG_at

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Date:   Tue, 25 Jul 2017 22:37:52 -0400
From:   Daniel Micay <danielmicay@...il.com>
To:     Kees Cook <keescook@...omium.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     kernel test robot <xiaolong.ye@...el.com>,
        Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Mark Rutland <mark.rutland@....com>,
        Daniel Axtens <dja@...ens.net>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Chris Metcalf <cmetcalf@...hip.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>, LKP <lkp@...org>,
        Joe Perches <joe@...ches.com>
Subject: Re: [lkp-robot] [include/linux/string.h] 6974f0c455:
 kernel_BUG_at_lib/string.c

It was known that there are going to be bugs to work through, many of
them relatively benign like the leaks of data near string constants
(probably other string constants) in rodata. It makes sense to have it
default to WARN with BUG / noreturn as a non-default configuration
option for it, I guess with !COMPILE_TEST like UBSAN_SANITIZE_ALL. I
don't think there's any sane way to bound the length of either reads /
writes. It needs to either WARN + continue on into doing the overflow or
use BUG. Trying to correct it might make things worse and would make
this more complicated / bug-prone. It already has enough subtle edge
cases to deal with.

I think 'benign' is a better term than 'false positive' because there
hasn't been a non-bug found yet. They're mostly not security vulns but
they're undefined behavior.