linux-kernel - Re: [PATCH 1/4] lockdep: lock_set

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]

Message-ID: <20111107162159.GC13699@google.com>
Date:	Mon, 7 Nov 2011 08:21:59 -0800
From:	Tejun Heo <tj@...nel.org>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Vegard Nossum <vegard.nossum@...il.com>,
	Yong Zhang <yong.zhang0@...il.com>,
	linux-kernel@...r.kernel.org, sergey.senozhatsky@...il.com,
	bp@...en8.de, Ingo Molnar <mingo@...e.hu>,
	David Rientjes <rientjes@...gle.com>,
	casteyde.christian@...e.fr
Subject: Re: [PATCH 1/4] lockdep: lock_set_subclass() fix

Hello,

On Mon, Nov 07, 2011 at 05:10:29PM +0100, Peter Zijlstra wrote:
> We could move the key and name pointer to the start of the structure and
> memset everything after that, however wouldn't that leave kmemcheck with
> the same problem? It wouldn't know those two pointers would be
> initialized properly.

At that point, lockdep_map is guaranteed to have passed through
lockdep_init_map(), so I think it should be fine.

> @@ -148,9 +148,9 @@ void clear_lock_stats(struct lock_class *class);
>   * This is embedded into specific lock instances:
>   */
>  struct lockdep_map {
> +	const char			*name;
>  	struct lock_class_key		*key;
>  	struct lock_class		*class_cache[NR_LOCKDEP_CACHING_CLASSES];
> -	const char			*name;
>  #ifdef CONFIG_LOCK_STAT
>  	int				cpu;
>  	unsigned long			ip;

Probably fat comment explaining the ordering requirement here w/

#define LOCKDEP_MAP_INIT_OFFSET		offsetof(struct lockdep_map, class_cache)

> diff --git a/kernel/lockdep.c b/kernel/lockdep.c
> index e69434b..81855cf 100644
> --- a/kernel/lockdep.c
> +++ b/kernel/lockdep.c
> @@ -2948,7 +2948,8 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
>  void lockdep_init_map(struct lockdep_map *lock, const char *name,
>  		      struct lock_class_key *key, int subclass)
>  {
> -	memset(lock, 0, sizeof(*lock));
> +	kmemcheck_mark_initialized(lock, 2*sizeof(void *));
> +	memset(&lock->class_cache[0], 0, sizeof(*lock)-2*sizeof(void *));

And something like the following?

	memset((void *)lock + LOCKDEP_MAP_INIT_OFFSET, 0,
		sizeof(*lock) - LOCKDEP_MAP_INIT_OFFSET);

Thanks.

-- 
tejun
--
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/