From: mike stump <mrs@windriver.com>
To: eager@mvista.com, fw@deneb.enyo.de
Cc: gcc@gcc.gnu.org, jsm28@cam.ac.uk
Subject: Re: Buffer Overflow Attacks
Date: Thu, 18 Oct 2001 17:00:00 -0000 [thread overview]
Message-ID: <200110182359.QAA00865@kankakee.wrs.com> (raw)
> Date: Thu, 18 Oct 2001 15:02:24 -0700
> From: Michael Eager <eager@mvista.com>
> To: Florian Weimer <fw@deneb.enyo.de>
> CC: "Joseph S. Myers" <jsm28@cam.ac.uk>, gcc@gcc.gnu.org
> I think that this is stretching reading of this paragraph. Creating
> a valid pointer address does not mean that deferencing the pointer is
> defined.
Well, I can't comment on the exact code you gave, but I can comment on
C++ and code like this:
struct foo {
char c[31];
int i;
} f;
*(((char*)&f)+32) and *(((char*)&f)+33) are allowed.
C must have the same rules for this case. If they don't they got it wrong.
> Referencing these padding bytes is undefined.
Nope. See above. Let's suppose that there are 16 bytes of padding in
there. The two expressions about, must work.
> Indeed, in a hypothetical processor with very fine grained memory
> protection, any padding bytes placed between c and i in the struct
> may be both unreadable and/or unwritable.
Nope. Cannot be done in C++. If C doesn't say this, it is wrong.
next reply other threads:[~2001-10-18 17:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-10-18 17:00 mike stump [this message]
2001-10-31 10:01 ` Florian Weimer
-- strict thread matches above, loose matches on Subject: below --
2001-10-31 16:39 mike stump
2001-10-14 12:25 dewar
2001-10-14 8:01 dewar
2001-10-14 10:25 ` Florian Weimer
2001-10-14 11:08 ` Joseph S. Myers
2001-10-14 12:14 ` Florian Weimer
2001-10-14 12:29 ` Joseph S. Myers
2001-10-18 15:02 ` Michael Eager
2001-10-14 5:32 Frank Pilhofer
2001-10-14 7:33 ` Carlo Wood
2001-10-14 10:50 ` Florian Weimer
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