linux-kernel - Re: [PATCH] tty: add lockdep annotations

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: <1338574627.2760.1545.camel@edumazet-glaptop>
Date:	Fri, 01 Jun 2012 20:17:07 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alan Cox <alan@...ux.intel.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Jens Axboe <jaxboe@...ionio.com>
Subject: Re: [PATCH] tty: add lockdep annotations

On Thu, 2012-05-31 at 11:35 +0200, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
> 
> tty_lock_pair() do the right thing to avoid deadlocks, but should
> instruct LOCKDEP of this to avoid a splat. 
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> ---
> Latest Linus tree still hang on my machine, at least this patch removes
> the lockdep problem...

About 10% of boots on my machine, and this looks like (hand written)

general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
...
RIP : tty_shutdown+0x15/)x70

Call Trace:

	con_shutdown+0x3e/0x50
	queue_release_one_tty+0x24/0x70
	tty_kref_put+0x28/0x30
	tty_unlock+0x2a/0x60
	tty_open+0x4d8/0x620
	chrdev_open+0xb1/0x1a0
...

Sometime stack is :
memset()
alloc_tty_struct
pty_unix98_install
tty_init_dev
ptmx_open
chrdev_open


I suspect a refcounting problem, but am not familiar enough with tty
code....



--
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/