linux-kernel - Re: [PATCH 2/2] sched: BUG when stack end location is over written

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:	Thu, 4 Sep 2014 17:32:31 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Aaron Tomlin <atomlin@...hat.com>
Cc:	mingo@...hat.com, dzickus@...hat.com, bmr@...hat.com,
	jcastillo@...hat.com, oleg@...hat.com, pzijlstr@...hat.com,
	riel@...hat.com, linux-kernel@...r.kernel.org, tglx@...utronix.de,
	x86@...nel.org, rostedt@...dmis.org, hannes@...xchg.org,
	aneesh.kumar@...ux.vnet.ibm.com, akpm@...ux-foundation.org,
	linuxppc-dev@...ts.ozlabs.org, minchan@...nel.org
Subject: Re: [PATCH 2/2] sched: BUG when stack end location is over written

On Thu, Sep 04, 2014 at 03:50:24PM +0100, Aaron Tomlin wrote:
> Currently in the event of a stack overrun a call to schedule()
> does not check for this type of corruption. This corruption is
> often silent and can go unnoticed. However once the corrupted
> region is examined at a later stage, the outcome is undefined
> and often results in a sporadic page fault which cannot be
> handled.
> 
> This patch checks for a stack overrun and takes appropriate
> action since the damage is already done, there is no point
> in continuing.
> 
> Signed-off-by: Aaron Tomlin <atomlin@...hat.com>
> ---
>  kernel/sched/core.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index ec1a286..d6af6a0 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -2660,6 +2660,9 @@ static noinline void __schedule_bug(struct task_struct *prev)
>   */
>  static inline void schedule_debug(struct task_struct *prev)
>  {
> +	if (unlikely(prev != &init_task &&
> +		task_stack_end_corrupted(prev)))
> +		BUG();

superfluous linebreak, also we appear to have BUG_ON() for situations
just like these.

secondly, while I appreciate the 'feature' you're making schedule()
slower for everybody, what do you propose to do about that?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/