linux-kernel - Re: [PATCH v6 17/25] PCI: Fix PREL32 relocations for LTO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 14 Oct 2020 15:58:12 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux@...glegroups.com,
        kernel-hardening@...ts.openwall.com, linux-arch@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        x86@...nel.org
Subject: Re: [PATCH v6 17/25] PCI: Fix PREL32 relocations for LTO

On Mon, Oct 12, 2020 at 05:31:55PM -0700, Sami Tolvanen wrote:
> With Clang's Link Time Optimization (LTO), the compiler can rename
> static functions to avoid global naming collisions. As PCI fixup
> functions are typically static, renaming can break references
> to them in inline assembly. This change adds a global stub to
> DECLARE_PCI_FIXUP_SECTION to fix the issue when PREL32 relocations
> are used.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
> Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
> Reviewed-by: Kees Cook <keescook@...omium.org>

Another independent patch! :) Bjorn, since you've already Acked this
patch, would be be willing to pick it up for your tree?

-Kees

> ---
>  include/linux/pci.h | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 835530605c0d..4e64421981c7 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1909,19 +1909,28 @@ enum pci_fixup_pass {
>  };
>  
>  #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
> -#define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class,	\
> -				    class_shift, hook)			\
> -	__ADDRESSABLE(hook)						\
> +#define ___DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class,	\
> +				    class_shift, hook, stub)		\
> +	void stub(struct pci_dev *dev);					\
> +	void stub(struct pci_dev *dev)					\
> +	{ 								\
> +		hook(dev); 						\
> +	}								\
>  	asm(".section "	#sec ", \"a\"				\n"	\
>  	    ".balign	16					\n"	\
>  	    ".short "	#vendor ", " #device "			\n"	\
>  	    ".long "	#class ", " #class_shift "		\n"	\
> -	    ".long "	#hook " - .				\n"	\
> +	    ".long "	#stub " - .				\n"	\
>  	    ".previous						\n");
> +
> +#define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class,	\
> +				  class_shift, hook, stub)		\
> +	___DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class,	\
> +				  class_shift, hook, stub)
>  #define DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class,	\
>  				  class_shift, hook)			\
>  	__DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class,	\
> -				  class_shift, hook)
> +				  class_shift, hook, __UNIQUE_ID(hook))
>  #else
>  /* Anonymous variables would be nice... */
>  #define DECLARE_PCI_FIXUP_SECTION(section, name, vendor, device, class,	\
> -- 
> 2.28.0.1011.ga647a8990f-goog
> 

-- 
Kees Cook