From: "Fāng-ruì Sòng" <maskray@google.com>
To: Alexander Lobakin <alobakin@pm.me>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Nathan Chancellor <natechancellor@gmail.com>,
Kees Cook <keescook@chromium.org>,
Jiaxun Yang <jiaxun.yang@flygoat.com>,
Alex Smith <alex.smith@imgtec.com>,
Ralf Baechle <ralf@linux-mips.org>,
Markos Chandras <markos.chandras@imgtec.com>,
linux-mips <linux-mips@vger.kernel.org>,
"# 3.4.x" <stable@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 mips-next 3/4] MIPS: vmlinux.lds.S: catch bad .got, .plt and .rel.dyn at link time
Date: Wed, 6 Jan 2021 12:21:53 -0800 [thread overview]
Message-ID: <CAFP8O3LBM-qSaM0ij7cEoP-s-zDaEG_VApbKonenCTrSxmJw+w@mail.gmail.com> (raw)
In-Reply-To: <20210106200801.31993-3-alobakin@pm.me>
On Wed, Jan 6, 2021 at 12:08 PM Alexander Lobakin <alobakin@pm.me> wrote:
>
> Catch any symbols placed in .got, .got.plt, .plt, .rel.dyn
> or .rela.dyn and check for these sections to be zero-sized
> at link time.
>
> At least two of them were noticed in real builds:
>
> mips-alpine-linux-musl-ld: warning: orphan section `.rel.dyn'
> from `init/main.o' being placed in section `.rel.dyn'
>
> ld.lld: warning: <internal>:(.got) is being placed in '.got'
>
> Adopted from x86/kernel/vmlinux.lds.S.
>
> Reported-by: Nathan Chancellor <natechancellor@gmail.com> # .got
> Suggested-by: Fangrui Song <maskray@google.com> # .rel.dyn
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
> ---
> arch/mips/kernel/vmlinux.lds.S | 35 ++++++++++++++++++++++++++++++++++
> 1 file changed, 35 insertions(+)
>
> diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
> index 5d6563970ab2..05eda9d9a7d5 100644
> --- a/arch/mips/kernel/vmlinux.lds.S
> +++ b/arch/mips/kernel/vmlinux.lds.S
> @@ -227,4 +227,39 @@ SECTIONS
> *(.pdr)
> *(.reginfo)
> }
> +
> + /*
> + * Sections that should stay zero sized, which is safer to
> + * explicitly check instead of blindly discarding.
> + */
> +
> + .got : {
> + *(.got)
> + *(.igot.*)
> + }
> + ASSERT(SIZEOF(.got) == 0, "Unexpected GOT entries detected!")
> +
> + .got.plt (INFO) : {
> + *(.got.plt)
> + }
> + ASSERT(SIZEOF(.got.plt) == 0, "Unexpected GOT/PLT entries detected!")
(INFO) drops the SHF_ALLOC flag from the output section (It does not
mean "informational"). INFO is not need here.
The diff from 815d680771ae09080d2da83dac2647c08cdf99ce "x86/build:
Enforce an empty .got.plt section" is not needed.
> + .plt : {
> + *(.plt)
> + *(.plt.*)
> + *(.iplt)
> + }
> + ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!")
> +
> + .rel.dyn : {
> + *(.rel.*)
> + *(.rel_*)
> + }
> + ASSERT(SIZEOF(.rel.dyn) == 0, "Unexpected run-time relocations (.rel) detected!")
> +
> + .rela.dyn : {
> + *(.rela.*)
> + *(.rela_*)
> + }
> + ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!")
> }
x86 has both .rel.dyn and .rela.dyn because i386 psABI uses REL while
x86-64 psABI uses RELA, but mips does not need .rela.dyn
> --
> 2.30.0
>
>
next prev parent reply other threads:[~2021-01-06 20:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-06 20:07 [PATCH v2 mips-next 0/4] MIPS: vmlinux.lds.S sections fix & cleanup Alexander Lobakin
2021-01-06 20:08 ` [PATCH v2 mips-next 1/4] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Alexander Lobakin
2021-01-06 20:08 ` [PATCH v2 mips-next 2/4] MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS Alexander Lobakin
2021-01-06 22:07 ` Kees Cook
2021-01-06 22:36 ` Alexander Lobakin
2021-01-06 23:26 ` Kees Cook
2021-01-07 11:59 ` Alexander Lobakin
2021-01-06 22:43 ` Fāng-ruì Sòng
2021-01-06 20:08 ` [PATCH v2 mips-next 3/4] MIPS: vmlinux.lds.S: catch bad .got, .plt and .rel.dyn at link time Alexander Lobakin
2021-01-06 20:21 ` Fāng-ruì Sòng [this message]
2021-01-06 20:23 ` Nathan Chancellor
2021-01-06 20:28 ` Alexander Lobakin
2021-01-06 20:08 ` [PATCH v2 mips-next 4/4] MIPS: select ARCH_WANT_LD_ORPHAN_WARN Alexander Lobakin
2021-01-06 22:07 ` Kees Cook
2021-01-06 22:07 ` [PATCH v2 mips-next 1/4] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAFP8O3LBM-qSaM0ij7cEoP-s-zDaEG_VApbKonenCTrSxmJw+w@mail.gmail.com \
--to=maskray@google.com \
--cc=alex.smith@imgtec.com \
--cc=alobakin@pm.me \
--cc=jiaxun.yang@flygoat.com \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=markos.chandras@imgtec.com \
--cc=natechancellor@gmail.com \
--cc=ralf@linux-mips.org \
--cc=stable@vger.kernel.org \
--cc=tsbogend@alpha.franken.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).