From: Kees Cook <keescook@chromium.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Arvind Sankar <nivedita@alum.mit.edu>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Thomas Lendacky <Thomas.Lendacky@amd.com>,
Mauro Rossi <issor.oruam@gmail.com>, Michael Matz <matz@suse.de>
Subject: Re: [PATCH v3] x86/vmlinux: Fix vmlinux.lds.S with pre-2.23 binutils
Date: Mon, 13 Jan 2020 18:20:12 -0800 [thread overview]
Message-ID: <202001131819.5A0031F611@keescook> (raw)
In-Reply-To: <261ae869-4169-296e-f673-5c08ff34bdde@zytor.com>
On Mon, Jan 13, 2020 at 05:57:23PM -0800, H. Peter Anvin wrote:
> On 2020-01-13 17:53, Kees Cook wrote:>>
> >> diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
> >> index 3a1a819da137..bad4e22384dc 100644
> >> --- a/arch/x86/kernel/vmlinux.lds.S
> >> +++ b/arch/x86/kernel/vmlinux.lds.S
> >> @@ -144,10 +144,12 @@ SECTIONS
> >> *(.text.__x86.indirect_thunk)
> >> __indirect_thunk_end = .;
> >> #endif
> >> +
> >> + /* End of text section */
> >> + _etext = .;
> >> } :text =0xcccc
> >>
> >> - /* End of text section, which should occupy whole number of pages */
> >> - _etext = .;
> >> + /* .text should occupy whole number of pages */
> >> . = ALIGN(PAGE_SIZE);
> >
> > NAK: linkers can add things at the end of .text that will go missing from
> > the kernel if _etext isn't _outside_ the .text section, truly beyond the
> > end of the .text section. This patch will break Control Flow Integrity
> > checking since the jump tables are at the end of .text.
> >
> > Boris, we're always working around weird linker problems; I don't see a
> > problem with the v2 patch to fix up old binutils...
> >
>
> Why not add the marker into a separate section instead of leaving it as an
> absolute "floater"? Very old binutils would botch that case, but I think that
> has been long since addressed well below our current minimum version.
Can you send a patch with what you're thinking?
--
Kees Cook
next prev parent reply other threads:[~2020-01-14 2:20 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-10 20:23 [PATCH] x86/tools/relocs: Add _etext and __end_of_kernel_reserve to S_REL Arvind Sankar
2020-01-10 20:38 ` Borislav Petkov
2020-01-10 20:50 ` Arvind Sankar
2020-01-10 21:50 ` [PATCH v2] " Arvind Sankar
2020-01-10 21:52 ` Arvind Sankar
2020-01-11 13:02 ` [PATCH] " Borislav Petkov
2020-01-11 17:20 ` Arvind Sankar
2020-01-11 17:32 ` Arvind Sankar
2020-01-13 13:43 ` Borislav Petkov
2020-01-13 16:13 ` Arvind Sankar
2020-01-13 16:38 ` Borislav Petkov
2020-01-13 17:59 ` Arvind Sankar
2020-01-13 18:08 ` Borislav Petkov
2020-01-14 4:17 ` Arvind Sankar
2020-01-14 11:25 ` Borislav Petkov
2020-01-14 16:32 ` Arvind Sankar
2020-01-14 4:08 ` Arvind Sankar
2020-01-13 19:53 ` [PATCH v3] x86/vmlinux: Fix vmlinux.lds.S with pre-2.23 binutils Arvind Sankar
2020-01-13 21:46 ` Tom Lendacky
2020-01-13 23:06 ` Arvind Sankar
2020-01-14 1:53 ` Kees Cook
2020-01-14 1:57 ` H. Peter Anvin
2020-01-14 2:20 ` Kees Cook [this message]
2020-01-14 3:58 ` Arvind Sankar
2020-01-14 5:05 ` hpa
2020-01-14 16:51 ` Borislav Petkov
2020-01-14 21:50 ` hpa
2020-01-15 0:21 ` Arvind Sankar
2020-01-15 12:24 ` Borislav Petkov
2020-03-16 16:02 ` [PATCH] Documentation/changes: Raise minimum supported binutils version to 2.23 Borislav Petkov
2020-03-16 20:54 ` Kees Cook
2020-03-23 20:44 ` Jason A. Donenfeld
2020-03-23 20:51 ` Kees Cook
2020-03-23 21:11 ` Jason A. Donenfeld
2020-03-25 17:33 ` David Laight
2020-03-24 9:02 ` Masahiro Yamada
2020-03-24 9:12 ` Masahiro Yamada
2020-03-24 15:38 ` Arvind Sankar
2020-03-24 17:31 ` Masahiro Yamada
2020-03-24 21:36 ` Arvind Sankar
2020-03-24 9:14 ` Borislav Petkov
2020-03-24 9:40 ` Masahiro Yamada
2020-03-24 12:00 ` Borislav Petkov
2020-03-24 16:22 ` Jason A. Donenfeld
2020-03-24 16:28 ` Borislav Petkov
2020-03-24 16:37 ` Linus Torvalds
2020-03-24 16:48 ` Borislav Petkov
2020-03-24 21:42 ` Arvind Sankar
2020-03-24 22:01 ` Arvind Sankar
2020-03-24 22:14 ` Linus Torvalds
2020-03-24 23:49 ` Arvind Sankar
2020-03-24 17:53 ` Kees Cook
2020-03-23 20:50 ` [PATCH] Documentation/changes: Raise minimum supported binutilsa " Nick Desaulniers
2020-01-13 23:38 ` [PATCH] x86/tools/relocs: Add _etext and __end_of_kernel_reserve to S_REL Arvind Sankar
2020-01-10 20:56 ` Kees Cook
[not found] ` <CAEQFVGa4fksPRtiLtBckSgbJY_JSHr07hoy5+5w-pAYym16YVg@mail.gmail.com>
2020-01-11 19:40 ` Fwd: " Mauro Rossi
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