linux-hardening - [PATCH v4 0/6] binfmt_elf: Support segments with 0 filesz and misaligned starts

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Date: Thu, 28 Sep 2023 20:24:28 -0700
From: Kees Cook <keescook@...omium.org>
To: Eric Biederman <ebiederm@...ssion.com>
Cc: Kees Cook <keescook@...omium.org>,
	Sebastian Ott <sebott@...hat.com>,
	Thomas Weißschuh <linux@...ssschuh.net>,
	Pedro Falcato <pedro.falcato@...il.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org,
	linux-hardening@...r.kernel.org
Subject: [PATCH v4 0/6] binfmt_elf: Support segments with 0 filesz and misaligned starts

Hi,

This is the continuation of the work Eric started for handling
"p_memsz > p_filesz" in arbitrary segments (rather than just the last,
BSS, segment). I've added the suggested changes:

 - drop unused "elf_bss" variable
 - refactor load_elf_interp() to use elf_load()
 - refactor load_elf_library() to use elf_load()
 - report padzero() errors when PROT_WRITE is present
 - drop vm_brk()

Thanks!

-Kees

v4:
 - refactor load_elf_library() too
 - don't refactor padzero(), just test in the only remaining caller
 - drop now-unused vm_brk()
v3: https://lore.kernel.org/all/20230927033634.make.602-kees@kernel.org
v2: https://lore.kernel.org/lkml/87sf71f123.fsf@email.froward.int.ebiederm.org
v1: https://lore.kernel.org/lkml/87jzsemmsd.fsf_-_@email.froward.int.ebiederm.org

Eric W. Biederman (1):
  binfmt_elf: Support segments with 0 filesz and misaligned starts

Kees Cook (5):
  binfmt_elf: elf_bss no longer used by load_elf_binary()
  binfmt_elf: Use elf_load() for interpreter
  binfmt_elf: Use elf_load() for library
  binfmt_elf: Only report padzero() errors when PROT_WRITE
  mm: Remove unused vm_brk()

 fs/binfmt_elf.c    | 214 ++++++++++++++++-----------------------------
 include/linux/mm.h |   3 +-
 mm/mmap.c          |   6 --
 mm/nommu.c         |   5 --
 4 files changed, 76 insertions(+), 152 deletions(-)

-- 
2.34.1