From: Masahiro Yamada <masahiroy@kernel.org>
To: Alexander Lobakin <alexandr.lobakin@intel.com>
Cc: linux-hardening@vger.kernel.org, X86 ML <x86@kernel.org>,
Borislav Petkov <bp@alien8.de>,
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Subject: Re: [PATCH v10 01/15] modpost: fix removing numeric suffixes
Date: Tue, 24 May 2022 22:40:51 +0900 [thread overview]
Message-ID: <CAK7LNAQus0vcWLCgSdMZNcYKam4fKYj9c8Zrb3HggZ7dTBUrxQ@mail.gmail.com> (raw)
In-Reply-To: <20220524113337.4128239-1-alexandr.lobakin@intel.com>
On Tue, May 24, 2022 at 8:34 PM Alexander Lobakin
<alexandr.lobakin@intel.com> wrote:
>
> From: Masahiro Yamada <masahiroy@kernel.org>
> Date: Tue, 24 May 2022 03:04:00 +0900
>
> > On Thu, Feb 10, 2022 at 3:59 AM Alexander Lobakin
> > <alexandr.lobakin@intel.com> wrote:
> > >
> > > `-z unique-symbol` linker flag which is planned to use with FG-KASLR
> > > to simplify livepatching (hopefully globally later on) triggers the
> > > following:
> > >
> > > ERROR: modpost: "param_set_uint.0" [vmlinux] is a static EXPORT_SYMBOL
> > >
> > > The reason is that for now the condition from remove_dot():
> > >
> > > if (m && (s[n + m] == '.' || s[n + m] == 0))
> > >
> > > which was designed to test if it's a dot or a '\0' after the suffix
> > > is never satisfied.
> > > This is due to that `s[n + m]` always points to the last digit of a
> > > numeric suffix, not on the symbol next to it (from a custom debug
> > > print added to modpost):
> > >
> > > param_set_uint.0, s[n + m] is '0', s[n + m + 1] is '\0'
> > >
> > > So it's off-by-one and was like that since 2014.
> > > Fix this for the sake of upcoming features, but don't bother
> > > stable-backporting, as it's well hidden -- apart from that LD flag,
> > > can be triggered only by GCC LTO which never landed upstream.
> > >
> > > Fixes: fcd38ed0ff26 ("scripts: modpost: fix compilation warning")
> > > Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
> > > ---
> > > scripts/mod/modpost.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> > > index 6bfa33217914..4648b7afe5cc 100644
> > > --- a/scripts/mod/modpost.c
> > > +++ b/scripts/mod/modpost.c
> > > @@ -1986,7 +1986,7 @@ static char *remove_dot(char *s)
> > >
> > > if (n && s[n]) {
> > > size_t m = strspn(s + n + 1, "0123456789");
> > > - if (m && (s[n + m] == '.' || s[n + m] == 0))
> > > + if (m && (s[n + m + 1] == '.' || s[n + m + 1] == 0))
> > > s[n] = 0;
> > >
> > > /* strip trailing .lto */
> > > --
> > > 2.34.1
> > >
> >
> > This trivial patch has not been picked up yet.
> >
> > I can apply this to my tree, if you want.
>
> It's a good idea, I'd like to!
> I don't use `-z unique-symbol` for FG-KALSR anymore*, but this fix
> is not directly related to it and can be taken independently.
> Should I change the commit message or it's ok to take it as it is?
I am fine with either way.
If you want to resubmit this with a fresh commit log,
please send it to:
linux-kbuild@vger.kernel.org
Then, I will take care of it in this MW.
Thanks.
> >
> > Please let me know your thoughts.
> >
> >
> > --
> > Best Regards
> > Masahiro Yamada
>
> * I'm planning to submit a new rev of FG-KASLR series soon, but
> since I'm too busy with XDP for now, it will happen no sooner than
> in a couple months =\
>
> Thanks!
> Al
--
Best Regards
Masahiro Yamada
next prev parent reply other threads:[~2022-05-24 13:46 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-09 18:57 [PATCH v10 00/15] Function Granular KASLR Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 01/15] modpost: fix removing numeric suffixes Alexander Lobakin
2022-05-03 0:57 ` Masahiro Yamada
2022-05-03 7:31 ` Petr Mladek
2022-05-23 18:04 ` Masahiro Yamada
2022-05-24 11:33 ` Alexander Lobakin
2022-05-24 13:40 ` Masahiro Yamada [this message]
2022-02-09 18:57 ` [PATCH v10 02/15] livepatch: avoid position-based search if `-z unique-symbol` is available Alexander Lobakin
2022-02-11 17:41 ` Josh Poimboeuf
2022-02-11 18:05 ` Fāng-ruì Sòng
2022-02-11 18:35 ` Josh Poimboeuf
2022-02-14 12:24 ` Alexander Lobakin
2022-02-14 18:10 ` Josh Poimboeuf
2022-02-16 20:32 ` Joe Lawrence
2022-02-16 22:13 ` Josh Poimboeuf
2022-02-16 15:15 ` Miroslav Benes
2022-02-16 20:01 ` Josh Poimboeuf
2022-02-18 16:31 ` Alexander Lobakin
2022-02-18 20:08 ` Josh Poimboeuf
2022-02-14 12:14 ` Alexander Lobakin
2022-02-14 18:57 ` Josh Poimboeuf
2022-02-16 15:06 ` Miroslav Benes
2022-02-16 19:57 ` Josh Poimboeuf
2022-02-17 7:45 ` Miroslav Benes
2022-02-09 18:57 ` [PATCH v10 03/15] kallsyms: randomize /proc/kallsyms output order Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 04/15] arch: introduce asm function sections Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 05/15] x86: support " Alexander Lobakin
2022-02-11 15:45 ` Peter Zijlstra
2022-02-14 11:49 ` Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 06/15] x86: decouple ORC table sorting into a separate file Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 07/15] Makefile: add config options and build scripts for FG-KASLR Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 08/15] x86/tools: Add relative relocs for randomized functions Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 09/15] x86: Add support for function granular KASLR Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 10/15] FG-KASLR: use a scripted approach to handle .text.* sections Alexander Lobakin
2022-02-11 15:37 ` Peter Zijlstra
2022-02-14 11:34 ` Alexander Lobakin
2022-02-14 11:59 ` Peter Zijlstra
2022-02-14 12:30 ` Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 11/15] x86/boot: allow FG-KASLR to be selected Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 12/15] module: add arch-indep FG-KASLR for randomizing function layout Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 13/15] module: use a scripted approach for FG-KASLR Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 14/15] Documentation: add documentation " Alexander Lobakin
2022-02-09 18:57 ` [PATCH v10 15/15] maintainers: add MAINTAINERS entry " Alexander Lobakin
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