netdev - Re: Use-after-free access in j1939_session

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Message-ID: <YO0Z7s8p7CoetxdW@kroah.com>
Date:   Tue, 13 Jul 2021 06:43:26 +0200
From:   Greg KH <greg@...ah.com>
To:     Xiaochen Zou <xzou017@....edu>
Cc:     kernel@...gutronix.de, linux-can@...r.kernel.org,
        netdev@...r.kernel.org, stable@...r.kernel.org
Subject: Re: Use-after-free access in j1939_session_deactivate

On Mon, Jul 12, 2021 at 03:40:46PM -0700, Xiaochen Zou wrote:
> Hi,
> It looks like there are multiple use-after-free accesses in
> j1939_session_deactivate()
> 
> static bool j1939_session_deactivate(struct j1939_session *session)
> {
> bool active;
> 
> j1939_session_list_lock(session->priv);
> active = j1939_session_deactivate_locked(session); //session can be freed inside
> j1939_session_list_unlock(session->priv); // It causes UAF read and write
> 
> return active;
> }
> 
> session can be freed by
> j1939_session_deactivate_locked->j1939_session_put->__j1939_session_release->j1939_session_destroy->kfree.
> Therefore it makes the unlock function perform UAF access.

Great, can you make up a patch to fix this issue so you can get credit
for finding and solving it?

thanks,

greg k-h