linux-kernel - Re: [PATCH] kernel/module.c: Mark module state before set RO and NX regions

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Date:	Wed, 07 Jan 2015 14:46:04 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Jungseung Lee <js07.lee@...il.com>, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Catalin Marinas <catalin.marinas@....com>,
	Russell King <rmk+kernel@....linux.org.uk>,
	Laura Abbott <lauraa@...eaurora.org>,
	Will Deacon <will.deacon@....com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Laura Abbott <lauraa@...eaurora.org>
Subject: Re: [PATCH] kernel/module.c: Mark module state before set RO and NX regions

Jungseung Lee <js07.lee@...il.com> writes:
> In some architectures like arm/arm64, set_memory_*() check module address
> and state as well. Mark module state before set RO and NX regions for
> the routine is passed.
>
> It will fix wrong RO/NX protection for loadable kernel modules on arm/arm64.

This partially reverts commit 4982223e51e8ea9d09bb33c8323b5ec1877b2b51
Author: Rusty Russell <rusty@...tcorp.com.au>
Date:   Wed May 14 10:54:19 2014 +0930

    module: set nx before marking module MODULE_STATE_COMING.

Laura Abbott (CC'd) was looking at an alternative fix for this.  Laura?

Thanks,
Rusty.

> Signed-off-by: Jungseung Lee <js07.lee@...il.com>
> ---
>  kernel/module.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 3965511..7e7cc9f 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -3152,6 +3152,10 @@ static int complete_formation(struct module *mod, struct load_info *info)
>  	/* This relies on module_mutex for list integrity. */
>  	module_bug_finalize(info->hdr, info->sechdrs, mod);
>  
> +	/* Mark state as coming so strong_try_module_get() ignores us,
> +	 * but kallsyms etc. can see us. */
> +	mod->state = MODULE_STATE_COMING;
> +
>  	/* Set RO and NX regions for core */
>  	set_section_ro_nx(mod->module_core,
>  				mod->core_text_size,
> @@ -3164,9 +3168,6 @@ static int complete_formation(struct module *mod, struct load_info *info)
>  				mod->init_ro_size,
>  				mod->init_size);
>  
> -	/* Mark state as coming so strong_try_module_get() ignores us,
> -	 * but kallsyms etc. can see us. */
> -	mod->state = MODULE_STATE_COMING;
>  	mutex_unlock(&module_mutex);
>  
>  	blocking_notifier_call_chain(&module_notify_list,
> -- 
> 1.9.1
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