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Date:   Fri, 29 Oct 2021 13:34:05 +0200
From:   Marc Kleine-Budde <mkl@pengutronix.de>
To:     Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Cc:     linux-can@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Matt Kline <matt@bitbashing.io>,
        Sean Nyekjaer <sean@geanix.com>,
        Chandrasekar Ramakrishnan <rcsekar@samsung.com>
Subject: Re: [RFC PATCH v1] can: m_can: m_can_read_fifo: fix memory leak in
 error branch
Message-ID: <20211029113405.hbqcu6chf5e3olrm@pengutronix.de>
References: <20211026180909.1953355-1-mailhol.vincent@wanadoo.fr>
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On 27.10.2021 03:09:09, Vincent Mailhol wrote:
> In m_can_read_fifo(), if the second call to m_can_fifo_read() fails,
> the function jump to the out_fail label and returns without calling
> m_can_receive_skb(). This means that the skb previously allocated by
> alloc_can_skb() is not freed. In other terms, this is a memory leak.
>=20
> This patch adds a new goto statement: out_receive_skb and do some
> small code refactoring to fix the issue.

This means we pass a skb to the user space, which contains wrong data.
Probably 0x0, but if the CAN frame doesn't contain 0x0, it's wrong. That
doesn't look like a good idea. If the CAN frame broke due to a CRC issue
on the wire it is not received. IMHO it's best to discard the skb and
return the error.

Marc

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Pengutronix e.K.                 | Marc Kleine-Budde           |
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