linux-kernel - Re: [PATCH net-next v2] net: dsa: avoid potential use-after-free error

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Date:   Fri, 20 Nov 2020 20:01:49 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Christian Eggers <ceggers@...i.de>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2] net: dsa: avoid potential use-after-free
 error

On Thu, Nov 19, 2020 at 12:09:06PM +0100, Christian Eggers wrote:
> If dsa_switch_ops::port_txtstamp() returns false, clone will be freed
> immediately. Shouldn't store a pointer to freed memory.
> 
> Signed-off-by: Christian Eggers <ceggers@...i.de>
> Fixes: 146d442c2357 ("net: dsa: Keep a pointer to the skb clone for TX timestamping")
> ---

IMO this is one of the cases to which the following from
Documentation/process/stable-kernel-rules.rst does not apply:

 - It must fix a real bug that bothers people (not a, "This could be a
   problem..." type thing).

Therefore, specifying "net-next" as the target tree here as opposed to
"net" is the correct choice.

Reviewed-by: Vladimir Oltean <olteanv@...il.com>
Tested-by: Vladimir Oltean <olteanv@...il.com>