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From: Max Filippov <jcmvbkbc@gmail.com>
Date: Mon, 5 Feb 2024 06:31:13 -0800
Message-ID: <CAMo8BfL+j5XUit2b7UjmZfZJCGd-gyh3Aia4FhLAm7YHNm0Fdg@mail.gmail.com>
Subject: Re: [PATCH] fs: binfmt_elf_efpic: don't use missing interpreter's properties
To: linux-kernel@vger.kernel.org
Cc: Chris Zankel <chris@zankel.net>, Alexander Viro <viro@zeniv.linux.org.uk>, 
	Christian Brauner <brauner@kernel.org>, Eric Biederman <ebiederm@xmission.com>, 
	Kees Cook <keescook@chromium.org>, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, 
	Greg Ungerer <gerg@linux-m68k.org>, Geert Uytterhoeven <geert@linux-m68k.org>
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Ping?

On Thu, Jan 18, 2024 at 7:07=E2=80=AFAM Max Filippov <jcmvbkbc@gmail.com> w=
rote:
>
> Static FDPIC executable may get an executable stack even when it has
> non-executable GNU_STACK segment. This happens when STACK segment has rw
> permissions, but does not specify stack size. In that case FDPIC loader
> uses permissions of the interpreter's stack, and for static executables
> with no interpreter it results in choosing the arch-default permissions
> for the stack.
>
> Fix that by using the interpreter's properties only when the interpreter
> is actually used.
>
> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
> ---
>  fs/binfmt_elf_fdpic.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
> index be4e7ac3efbc..f6d72fe3998c 100644
> --- a/fs/binfmt_elf_fdpic.c
> +++ b/fs/binfmt_elf_fdpic.c
> @@ -322,7 +322,7 @@ static int load_elf_fdpic_binary(struct linux_binprm =
*bprm)
>         else
>                 executable_stack =3D EXSTACK_DEFAULT;
>
> -       if (stack_size =3D=3D 0) {
> +       if (stack_size =3D=3D 0 && interp_params.flags & ELF_FDPIC_FLAG_P=
RESENT) {
>                 stack_size =3D interp_params.stack_size;
>                 if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK)
>                         executable_stack =3D EXSTACK_ENABLE_X;
> --
> 2.39.2
>


--=20
Thanks.
-- Max