[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20120314213746.GK23916@ZenIV.linux.org.uk>
Date: Wed, 14 Mar 2012 21:37:46 +0000
From: Al Viro <viro@...IV.linux.org.uk>
To: Sasha Levin <levinsasha928@...il.com>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
davej@...hat.com
Subject: Re: [PATCH] vfs namespace: Don't assume mount namespace has valid
root
On Wed, Mar 14, 2012 at 11:03:43PM +0200, Sasha Levin wrote:
> > And that's all pointers to mnt_namespace that ever exist, aside of function
> > arguments and local variables. ?I'm not saying that I couldn't have possibly
> > fucked it up, but from rereading that code it doesn't look like we could
> > end up with dangling pointers to already freed instances...
>
> I'm trying to find the exact chain of events leading it it at the
> moment, but it reproduces rather easily - so if you have any ideas on
> figuring it out I'm happy to try anything.
Which kernel, for starters? I'd probably add dumping call chain +
return value in alloc_mnt_ns(), call chain + pointer being freed in
final put_mnt_ns() and failure exit of dup_mnt_ns(), address of
mnt_ns and value assigned to ->root on assignments to ->root in
create_mnt_ns() and dup_mnt_ns() and mnt_ns in dup_mnt_ns() if it
happens to have NULL ->root.
That should give you full history of allocation/freeing mnt_namespace
instances and of assignments to anyone's ->root. Ought to make a sane
starting point...
--
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/
Powered by blists - more mailing lists