linux-kernel - Re: [PATCH 1/2] vsprintf: distinguish between (null), (err) and (invalid) pointer derefs

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Message-ID: <20180306182217.GA3798@avx2>
Date:   Tue, 6 Mar 2018 21:22:17 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     kilobyte@...band.pl
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] vsprintf: distinguish between (null), (err) and
 (invalid) pointer derefs

> +#define BAD_PTR_STRING(x) (!(x) ? "(null)" : IS_ERR(x) ? "(err)" : "(invalid)")

This is getting ridiculous.

Instead of simply printing a pointer as %08lx or %016llx, not only glibc
(null) stupidity is propagated but expanded and "improved".

I assure you reading 0000000000000000 is just as obvious as (null) and
reading fffffffffffffffa is just as good as -ENOMEM.

In fact printing with hex is more information. Maybe it is important
that buggy pointer is small value but it's value is lost.

Sure don't dereference a pointer for very small or very erry values
but print it without all the bell and whistles.