linux-kernel - Re: [RESEND PATCH v2] net/x25: Fix null-ptr-deref in x25

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Date:   Wed, 11 Nov 2020 03:38:05 -0800
From:   Xie He <xie.he.0141@...il.com>
To:     Martin Schiller <ms@....tdt.de>
Cc:     andrew.hendry@...il.com, davem@...emloft.net, kuba@...nel.org,
        edumazet@...gle.com, xiyuyang19@...an.edu.cn,
        linux-x25@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH v2] net/x25: Fix null-ptr-deref in x25_connect

> This fixes a regression for blocking connects introduced by commit
> 4becb7ee5b3d ("net/x25: Fix x25_neigh refcnt leak when x25 disconnect").

> The x25->neighbour is already set to "NULL" by x25_disconnect() now,
> while a blocking connect is waiting in
> x25_wait_for_connection_establishment(). Therefore x25->neighbour must
> not be accessed here again and x25->state is also already set to
> X25_STATE_0 by x25_disconnect().

> Fixes: 4becb7ee5b3d ("net/x25: Fix x25_neigh refcnt leak when x25 disconnect")
> Signed-off-by: Martin Schiller <ms@....tdt.de>

Oh. Sorry, I didn't see your patch. I just submitted another patch to fix
the same problem.

I also found another problem introduced by the same regression commit,
which I was also trying to fix in my patch.

See:
http://patchwork.ozlabs.org/project/netdev/patch/20201111100424.3989-1-xie.he.0141@gmail.com/