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From: "parker@cyber-itl.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/94158] Expanded strlen causes out-of-bounds read on
 AMD64 target
Date: Thu, 12 Mar 2020 21:59:34 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94158

--- Comment #3 from Parker Thompson <parker@cyber-itl.org> ---
(In reply to Andrew Pinski from comment #2)
> Also aligned_alloc normally does not allow alignment of 1.
>=20
> So GCC is doing the correct thing.

The replacement of strdup here is just to illustrate the issue with expansi=
on
alignment of strlen() by forcing a crash.

I encountered this issue when working with a custom malloc replacement that
would enforce out-of-bounds read checks. Using the same reproduction with c=
lang
did not produce a crash / oob-read.

As for alloc alignment, glibc strdup() does not use aligned_alloc, just mal=
loc.
 Which by my read of the spec does not guarantee alignment.=