netdev - Re: [PATCH net] net: avoid NULL deref in inet_ctl_sock

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Message-ID: <1446527041.23275.50.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Mon, 02 Nov 2015 21:04:01 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, dvyukov@...gle.com
Subject: Re: [PATCH net] net: avoid NULL deref in inet_ctl_sock_destroy()

On Mon, 2015-11-02 at 22:46 -0500, David Miller wrote:
> From: Eric Dumazet <eric.dumazet@...il.com>
> Date: Mon, 02 Nov 2015 07:50:07 -0800
> 
> > From: Eric Dumazet <edumazet@...gle.com>
> > 
> > Under low memory conditions, tcp_sk_init() and icmp_sk_init()
> > can both iterate on all possible cpus and call inet_ctl_sock_destroy(),
> > with eventual NULL pointer.
> > 
> > Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> > Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
> 
> Applied.

Thanks David.

Bug origin was in linux-4.2 :

commit 26abe14379f8e2fa3fd1bcf97c9a7ad9364886fe
Author: Eric W. Biederman <ebiederm@...ssion.com>
Date:   Fri May 8 21:10:31 2015 -0500

    net: Modify sk_alloc to not reference count the netns of kernel sockets.
    
    Now that sk_alloc knows when a kernel socket is being allocated modify
    it to not reference count the network namespace of kernel sockets.
    
    Keep track of if a socket needs reference counting by adding a flag to
    struct sock called sk_net_refcnt.
    
    Update all of the callers of sock_create_kern to stop using
    sk_change_net and sk_release_kernel as those hacks are no longer
    needed, to avoid reference counting a kernel socket.
    
    Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
    Signed-off-by: David S. Miller <davem@...emloft.net>



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