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From: "joseph at codesourcery dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug libc/25620] Signed comparison vulnerability in the ARMv7
 memcpy() (CVE-2020-6096)
Date: Tue, 07 Apr 2020 20:58:48 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D25620

--- Comment #14 from joseph at codesourcery dot com <joseph at codesourcery=
 dot com> ---
On Tue, 7 Apr 2020, wdijkstr at arm dot com via Glibc-bugs wrote:

> Yes, and it would be even better to check for overlap, that includes this=
 case
> and would find quite a few real bugs.

I think a de facto part of the ABI is that memcpy of an object to itself=20
(source and destination pointers equal) does work; some GCC versions may=20
generate that for structure assignment in some cases where it's not know=20
if there might be such exact overlap but partial overlap would not be=20
valid (which is the standard C rule for structure assignment).  (GCC won't=
=20
let you declare a type occupying half the address space or more, so the=20
structure assignment case isn't applicable for such a large memcpy.)

--=20
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