From: Richard Kojedzinszky <richard@kojedz.in>
To: Kees Cook <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, Ali Saidi <alisaidi@amazon.com>,
Guenter Roeck <linux@roeck-us.net>,
Michal Hocko <mhocko@suse.com>,
Matthew Wilcox <willy@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Jann Horn <jannh@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] binfmt_elf: Do not move brk for INTERP-less ET_EXEC
Date: Thu, 26 Sep 2019 20:26:12 +0200 [thread overview]
Message-ID: <cfdb3b68100025288177da8a963bc909@kojedz.in> (raw)
In-Reply-To: <201909261012.96DE554A@keescook>
Hi Kees,
Thanks for the quick patch. It seems my binaries start up well, and work
as expected, as before.
Thanks again for the quick response.
Regards,
Richard Kojedzinszky
2019-09-26 19:15 időpontban Kees Cook ezt írta:
> When brk was moved for binaries without an interpreter, it should have
> been limited to ET_DYN only. In other words, the special case was an
> ET_DYN that lacks an INTERP, not just an executable that lacks INTERP.
> The bug manifested for giant static executables, where the brk would
> end
> up in the middle of the text area on 32-bit architectures.
>
> Reported-by: Richard Kojedzinszky <richard@kojedz.in>
> Fixes: bbdc6076d2e5 ("binfmt_elf: move brk out of mmap when doing
> direct loader exec")
> Cc: stable@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> Richard, are you able to test this? I'm able to run the gitea binary
> with this change, and my INTERP-less ET_DYN tests (from the original
> bug) continue to pass as well.
> ---
> fs/binfmt_elf.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
> index cec3b4146440..ad4c6b1d5074 100644
> --- a/fs/binfmt_elf.c
> +++ b/fs/binfmt_elf.c
> @@ -1121,7 +1121,8 @@ static int load_elf_binary(struct linux_binprm
> *bprm)
> * (since it grows up, and may collide early with the stack
> * growing down), and into the unused ELF_ET_DYN_BASE region.
> */
> - if (IS_ENABLED(CONFIG_ARCH_HAS_ELF_RANDOMIZE) && !interpreter)
> + if (IS_ENABLED(CONFIG_ARCH_HAS_ELF_RANDOMIZE) &&
> + loc->elf_ex.e_type == ET_DYN && !interpreter)
> current->mm->brk = current->mm->start_brk =
> ELF_ET_DYN_BASE;
>
> --
> 2.17.1
next prev parent reply other threads:[~2019-09-26 18:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-26 17:15 [PATCH] binfmt_elf: Do not move brk for INTERP-less ET_EXEC Kees Cook
2019-09-26 18:26 ` Richard Kojedzinszky [this message]
2019-09-26 18:37 ` Kees Cook
2019-09-27 6:16 ` Richard Kojedzinszky
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