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Open Source and information security mailing list archives
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Date: Tue, 3 May 2022 09:31:07 +0200 From: Petr Mladek <pmladek@...e.com> To: Alexander Lobakin <alexandr.lobakin@...el.com> Cc: linux-hardening@...r.kernel.org, x86@...nel.org, Borislav Petkov <bp@...en8.de>, Jesse Brandeburg <jesse.brandeburg@...el.com>, Kristen Carlson Accardi <kristen@...ux.intel.com>, Kees Cook <keescook@...omium.org>, Miklos Szeredi <miklos@...redi.hu>, Ard Biesheuvel <ardb@...nel.org>, Tony Luck <tony.luck@...el.com>, Bruce Schlobohm <bruce.schlobohm@...el.com>, Jessica Yu <jeyu@...nel.org>, kernel test robot <lkp@...el.com>, Miroslav Benes <mbenes@...e.cz>, Evgenii Shatokhin <eshatokhin@...tuozzo.com>, Jonathan Corbet <corbet@....net>, Masahiro Yamada <masahiroy@...nel.org>, Michal Marek <michal.lkml@...kovi.net>, Nick Desaulniers <ndesaulniers@...gle.com>, Herbert Xu <herbert@...dor.apana.org.au>, "David S. Miller" <davem@...emloft.net>, Thomas Gleixner <tglx@...utronix.de>, Will Deacon <will@...nel.org>, Ingo Molnar <mingo@...hat.com>, Christoph Hellwig <hch@....de>, Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Arnd Bergmann <arnd@...db.de>, Josh Poimboeuf <jpoimboe@...hat.com>, Nathan Chancellor <nathan@...nel.org>, Masami Hiramatsu <mhiramat@...nel.org>, Marios Pomonis <pomonis@...gle.com>, Sami Tolvanen <samitolvanen@...gle.com>, "H.J. Lu" <hjl.tools@...il.com>, Nicolas Pitre <nico@...xnic.net>, linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org, linux-arch@...r.kernel.org, live-patching@...r.kernel.org, llvm@...ts.linux.dev Subject: Re: [PATCH v10 01/15] modpost: fix removing numeric suffixes On Wed 2022-02-09 19:57:38, Alexander Lobakin 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' Yup, the + 1 is for the '.' between the symbol name and the number. In the order of apperance it would be: n + 1 + m > 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@...el.com> Reviewed-by: Petr Mladek <pmladek@...e.com> Best Regards, Petr
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