netdev - Re: [PATCH net 2/2] net/tls: Fix use-after-free after the TLS device goes down and up

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Message-ID: <20210525102156.2b27205f@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Tue, 25 May 2021 10:21:56 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Maxim Mikityanskiy <maximmi@...dia.com>
Cc:     Boris Pismenny <borisp@...dia.com>,
        John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>,
        Aviad Yehezkel <aviadye@...dia.com>,
        "Tariq Toukan" <tariqt@...dia.com>, <netdev@...r.kernel.org>
Subject: Re: [PATCH net 2/2] net/tls: Fix use-after-free after the TLS
 device goes down and up

On Tue, 25 May 2021 11:52:31 +0300 Maxim Mikityanskiy wrote:
> > Can we have the Rx resync take the device_offload_lock for read instead?
> > Like Tx already does?  
> 
> I believe you previously made this attempt in commit 38030d7cb779 
> ("net/tls: avoid NULL-deref on resync during device removal"), and this 
> approach turned out to be problematic, as explained in commit 
> e52972c11d6b ("net/tls: replace the sleeping lock around RX resync with 
> a bit lock"): "RX resync may get called from soft IRQ, so we can't use 
> the rwsem".

If only my memory wasn't this shit.. :) Let me take a look at the patch
again.