linux-hardening - Re: (subset) [PATCH 2/2] binfmt_elf: Leave a gap between .bss and brk

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Date: Wed, 24 Apr 2024 12:20:58 -0700
From: Kees Cook <keescook@...omium.org>
To: Jiri Kosina <jikos@...nel.org>,
	Kees Cook <keescook@...omium.org>
Cc: y0un9n132@...il.com,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>,
	Jan Kara <jack@...e.cz>,
	Eric Biederman <ebiederm@...ssion.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Qi Zheng <zhengqi.arch@...edance.com>,
	Alexandre Ghiti <alexghiti@...osinc.com>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Rick Edgecombe <rick.p.edgecombe@...el.com>,
	Brian Gerst <brgerst@...il.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Tony Battersby <tonyb@...ernetics.com>,
	linux-kernel@...r.kernel.org,
	x86@...nel.org,
	linux-hardening@...r.kernel.org
Subject: Re: (subset) [PATCH 2/2] binfmt_elf: Leave a gap between .bss and brk

On Fri, 16 Feb 2024 22:25:44 -0800, Kees Cook wrote:
> Currently the brk starts its randomization immediately after .bss,
> which means there is a chance that when the random offset is 0, linear
> overflows from .bss can reach into the brk area. Leave at least a single
> page gap between .bss and brk (when it has not already been explicitly
> relocated into the mmap range).
> 
> 
> [...]

Patch 1/2 was already applied via x86 tip, so I'll grab this one for the execve/binfmt tree.

Applied to for-next/execve.

[2/2] binfmt_elf: Leave a gap between .bss and brk
      https://git.kernel.org/kees/c/2a5eb9995528

Take care,

-- 
Kees Cook