linux-kernel - Re: [PATCH 15/20] ufs: remove the BKL

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:	Tue, 25 Jan 2011 21:30:31 -0500
From:	Nick Bowler <nbowler@...iptictech.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	linux-kernel@...r.kernel.org, Evgeniy Dushistov <dushistov@...l.ru>
Subject: Re: [PATCH 15/20] ufs: remove the BKL

On 2011-01-25 23:17 +0100, Arnd Bergmann wrote:
> This introduces a new per-superblock mutex in UFS to replace
> the big kernel lock. I have been careful to avoid nested
> calls to lock_ufs and to get the lock order right with
> respect to other mutexes, in particular lock_super.
> 
> The code is still only compile-tested, but it should
> at least be harmless on non-SMP systems, since the
> new mutex is not taken on those.
[...]
> +void lock_ufs(struct super_block *sb)
> +{
> +#if defined(CONFIG_SMP) || defined (CONFIG_PREEMPT)
> +	struct ufs_sb_info *sbi = UFS_SB(sb);
> +
> +	mutex_lock(&sbi->mutex);
> +	sbi->mutex_owner = current;
> +#endif
> +}
> +
> +void unlock_ufs(struct super_block *sb)
> +{
> +#if defined(CONFIG_SMP) || defined (CONFIG_PREEMPT)
> +	struct ufs_sb_info *sbi = UFS_SB(sb);
> +
> +	sbi->mutex_owner = NULL;
> +	mutex_unlock(&sbi->mutex);
> +#endif
> +}

The sbi->mutex lock used by these functions is never initialized, which
causes an insta-crash on mount.  With a mutex_init call added to
ufs_fill_super, there are no obvious problems with my read-only
mounts after some (very light) testing.

-- 
Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)
--
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/