netdev - Re: [PATCH net] tls: fix NULL pointer dereference on poll

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Date:   Mon, 11 Jun 2018 16:30:50 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     daniel@...earbox.net
Cc:     davejwatson@...com, netdev@...r.kernel.org, ast@...nel.org,
        hch@....de
Subject: Re: [PATCH net] tls: fix NULL pointer dereference on poll

From: Daniel Borkmann <daniel@...earbox.net>
Date: Mon, 11 Jun 2018 23:22:04 +0200

> While hacking on kTLS, I ran into the following panic from an
> unprivileged netserver / netperf TCP session:
 ...
> Debugging further, it turns out that calling into ctx->sk_poll() is
> invalid since sk_poll itself is NULL which was saved from the original
> TCP socket in order for tls_sw_poll() to invoke it.
> 
> Looks like the recent conversion from poll to poll_mask callback started
> in 152524231023 ("net: add support for ->poll_mask in proto_ops") missed
> to eventually convert kTLS, too: TCP's ->poll was converted over to the
> ->poll_mask in commit 2c7d3dacebd4 ("net/tcp: convert to ->poll_mask")
> and therefore kTLS wrongly saved the ->poll old one which is now NULL.
> 
> Convert kTLS over to use ->poll_mask instead. Also instead of POLLIN |
> POLLRDNORM use the proper EPOLLIN | EPOLLRDNORM bits as the case in
> tcp_poll_mask() as well that is mangled here.
> 
> Fixes: 2c7d3dacebd4 ("net/tcp: convert to ->poll_mask")
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>

Applied, thanks Daniel.