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From: pageexec@freemail.hu
To: Ingo Molnar <mingo@elte.hu>
Cc: Sam Ravnborg <sam@ravnborg.org>,
	Arjan van de Ven <arjan@infradead.org>,
	linux-kernel@vger.kernel.org, torvalds@linux-foundation.org
Subject: Re: vmsplice exploits, stack protector and Makefiles
Date: Thu, 14 Feb 2008 12:23:38 +0200	[thread overview]
Message-ID: <47B432CA.28524.E15DB6A@pageexec.freemail.hu> (raw)
In-Reply-To: <20080214073003.GA25699@elte.hu>

On 14 Feb 2008 at 8:30, Ingo Molnar wrote:

> --- linux-x86.q.orig/arch/x86/kernel/process_64.c
> +++ linux-x86.q/arch/x86/kernel/process_64.c
> @@ -166,6 +166,15 @@ static inline void play_dead(void)
>  void cpu_idle(void)
>  {
>  	current_thread_info()->status |= TS_POLLING;
> +
> +#ifdef CONFIG_CC_STACKPROTECTOR
> +	/*
> +	 * If we're the non-boot CPU, nothing set the PDA stack
> +	 * canary up for us. This is as good a place as any for
> +	 * doing that.
> +	 */
> +	write_pda(stack_canary, current->stack_canary);
> +#endif

i wonder if these #ifdef's are really needed at all, even if one doesn't
use -fstack-protector, having the code set up the canary has like 0
performance impact. not to mention that i think the change in switch_to
means that it won't compile without CONFIG_CC_STACKPROTECTOR enabled and
instead of making that macro conditional it's just a lot easier to enable
the canary all the time.


  reply	other threads:[~2008-02-14 11:24 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-12 17:00 Arjan van de Ven
2008-02-12 18:50 ` Sam Ravnborg
2008-02-12 19:08   ` Arjan van de Ven
2008-02-12 19:36     ` Sam Ravnborg
2008-02-13 13:38 ` pageexec
2008-02-13 15:29   ` Ingo Molnar
2008-02-13 16:29     ` Randy Dunlap
2008-02-13 15:48       ` pageexec
2008-02-14 12:20         ` Jan Engelhardt
2008-02-13 16:48     ` Ingo Molnar
2008-02-13 16:15       ` pageexec
2008-02-14  6:16         ` Ingo Molnar
2008-02-14  7:30           ` Ingo Molnar
2008-02-14 10:23             ` pageexec [this message]
2008-02-13 15:53   ` Linus Torvalds
2008-02-13 16:01     ` Ingo Molnar
2008-02-13 17:16       ` Sam Ravnborg
2008-02-14  6:12         ` Ingo Molnar
2008-02-14  7:43   ` Sam Ravnborg

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