netdev - Re: [PATCH] net: Fix module refcount leak in kernel

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Message-Id: <20081218.223926.229583681.davem@davemloft.net>
Date:	Thu, 18 Dec 2008 22:39:26 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	marcel@...tmann.org
Cc:	yjwei@...fujitsu.com, netdev@...r.kernel.org
Subject: Re: [PATCH] net: Fix module refcount leak in kernel_accept()

From: Marcel Holtmann <marcel@...tmann.org>
Date: Fri, 19 Dec 2008 07:35:37 +0100

> Hi Wei,
> 
> > The kernel_accept() does not hold the module refcount of newsock->ops->owner,
> > so we need __module_get(newsock->ops->owner) code after call kernel_accept()
> > by hand.
> > In sunrpc, the module refcount is missing to hold. So this cause kernel panic.
> > 
> > Used following script to reproduct:
> > 
> > while [ 1 ];
> > do
> >     mount -t nfs4 192.168.0.19:/ /mnt
> >     touch /mnt/file
> >     umount /mnt
> >     lsmod | grep ipv6
> > done
> > 
> > This patch fixed the problem by add __module_get(newsock->ops->owner) to
> > kernel_accept(). So we do not need to used __module_get(newsock->ops->owner)
> > in every place when used kernel_accept().
> > 
> > Signed-off-by: Wei Yongjun <yjwei@...fujitsu.com>
> > ---
> >  net/bluetooth/rfcomm/core.c |    2 --
> >  net/socket.c                |    1 +
> >  2 files changed, 1 insertions(+), 2 deletions(-)
> 
> I was just about to reply and ask you to double check the users since I
> know that I am using that API. Hey, but you already did that. Thanks.

That's the exact audit I did before applying his patch :-)
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