linux-kernel - Re: [PATCH] fs: binfmt_elf_efpic: don't use missing interpreter's properties

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Date: Mon, 5 Feb 2024 06:31:13 -0800
From: Max Filippov <jcmvbkbc@...il.com>
To: linux-kernel@...r.kernel.org
Cc: Chris Zankel <chris@...kel.net>, Alexander Viro <viro@...iv.linux.org.uk>, 
	Christian Brauner <brauner@...nel.org>, Eric Biederman <ebiederm@...ssion.com>, 
	Kees Cook <keescook@...omium.org>, linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, 
	Greg Ungerer <gerg@...ux-m68k.org>, Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: Re: [PATCH] fs: binfmt_elf_efpic: don't use missing interpreter's properties

Ping?

On Thu, Jan 18, 2024 at 7:07 AM Max Filippov <jcmvbkbc@...il.com> wrote:
>
> 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@...il.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 = EXSTACK_DEFAULT;
>
> -       if (stack_size == 0) {
> +       if (stack_size == 0 && interp_params.flags & ELF_FDPIC_FLAG_PRESENT) {
>                 stack_size = interp_params.stack_size;
>                 if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK)
>                         executable_stack = EXSTACK_ENABLE_X;
> --
> 2.39.2
>


-- 
Thanks.
-- Max