netdev - Re: [PATCH net 2/2] ravb: Fix use-after-free issue in ravb_remove and ravb_tx_timeout

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Message-ID: <f4cf24ff-2576-6031-e482-ebd8fa1d9659@omp.ru>
Date: Wed, 4 Oct 2023 21:29:57 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>
CC: <netdev@...r.kernel.org>, <linux-renesas-soc@...r.kernel.org>, Zheng Wang
	<zyytlz.wz@....com>
Subject: Re: [PATCH net 2/2] ravb: Fix use-after-free issue in ravb_remove and
 ravb_tx_timeout_work

Hello!

   Hm, concerning the subject: don't we actually have use-after-free in ravb_tx_timeout()
only? Also, you place () after the function names in patch #1 but not in this patch, why?

On 10/4/23 12:12 PM, Yoshihiro Shimoda wrote:

> The ravb_stop() should call cancel_work_sync(). Otherwise,
> ravb_tx_timeout_work() is possible to use the freed priv after
> ravb_remove() was called like below:
> 
> CPU0			CPU1
> 			ravb_tx_timeout()
> ravb_remove()
> unregister_netdev()
> free_netdev(ndev)
> // free priv
> 			ravb_tx_timeout_work()
> 			// use priv
> 
> unregister_netdev() will call .ndo_stop() so that ravb_stop() is
> called. And, after phy_stop() was called, netif_carrier_off()

   s/was/is/?

> is also called. So that .ndo_tx_timeout() will be not called

   Will not be...

> after phy_stop().
> 
> Link: https://lore.kernel.org/netdev/872cf8d7-3bd6-b11a-82ac-a9f4c82d0a02@omp.ru/
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Reported-by: Zheng Wang <zyytlz.wz@....com>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>

   Otherwise:

Reviewed-by: Sergey Shtylyov <s.shtylyov@....ru>

[...]

MBR, Sergey