netdev - Re: [PATCH net] net: dsa: fix 'increment on 0' warning

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Date:   Fri, 24 Nov 2017 13:21:20 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Vivien Didelot <vivien.didelot@...oirfairelinux.com>,
        netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel@...oirfairelinux.com,
        "David S. Miller" <davem@...emloft.net>,
        Andrew Lunn <andrew@...n.ch>,
        Fengguang Wu <fengguang.wu@...el.com>, wfg@...ux.intel.com,
        LKP <lkp@...org>
Subject: Re: [PATCH net] net: dsa: fix 'increment on 0' warning



On 11/24/2017 08:36 AM, Vivien Didelot wrote:
> Setting the refcount to 0 when allocating a tree to match the number of
> switch devices it holds may cause an 'increment on 0; use-after-free',
> if CONFIG_REFCOUNT_FULL is enabled.
> 
> To fix this, do not decrement the refcount of a newly allocated tree,
> increment it when an already allocated tree is found, and decrement it
> after the probing of a switch, as done with the previous behavior.
> 
> At the same time, make dsa_tree_get and dsa_tree_put accept a NULL
> argument to simplify callers, and return the tree after incrementation,
> as most kref users like of_node_get and of_node_put do.
> 
> Fixes: 8e5bf9759a06 ("net: dsa: simplify tree reference counting")
> Signed-off-by: Vivien Didelot <vivien.didelot@...oirfairelinux.com>

Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
Tested-by: Florian Fainelli <f.fainelli@...il.com>

Thanks!
-- 
Florian