From: DJ Delorie <dj@redhat.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCH] malloc: Implement heap protector
Date: Fri, 28 Oct 2016 20:45:00 -0000 [thread overview]
Message-ID: <xn7f8snqwt.fsf@greed.delorie.com> (raw)
In-Reply-To: <dd818b8d-7176-8490-0780-e6e25756323a@redhat.com> (Florian Weimer's message of "Fri, 28 Oct 2016 15:17:22 +0200")
My only comments on this one are:
> +/* Decrypt a heap header chunk. */
> +#define HEAP_CRYPT_SIZE(val) (__malloc_header_guard ^ ((INTERNAL_SIZE_T) val))
> +#define HEAP_CRYPT_PREVSIZE(val) \
> + (__malloc_footer_guard ^ ((INTERNAL_SIZE_T) val))
For readability and maintainability, we should probably have both CRYPT
and DECRYPT macros, used correcly throughout. Yes, I know they'd be the
same now, but they might not be later.
> +/* The heap cookie. The lowest three bits (corresponding to
> + SIZE_BITS) in __malloc_guard_header must be clear. Initialized
> + during libc startup, and computed by elf/dl-keysetup.c. */
If the lowest three bits must be clear, we should either clear them or
assert that they're clear.
prev parent reply other threads:[~2016-10-28 20:45 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-28 13:17 Florian Weimer
2016-10-28 15:05 ` Carlos O'Donell
2016-10-28 17:56 ` Paul Eggert
2016-11-08 15:13 ` Florian Weimer
2016-11-08 16:09 ` Andreas Schwab
2016-11-10 15:39 ` Florian Weimer
2016-10-28 20:45 ` DJ Delorie [this message]
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