linux-kernel - Re: [PATCH] drivers/i2c-aspeed: avoid invalid memory reference after timeout

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Date:   Tue, 11 Jan 2022 15:52:25 +0800
From:   Heyi Guo <guoheyi@...ux.alibaba.com>
To:     linux-kernel@...r.kernel.org
Cc:     Brendan Higgins <brendanhiggins@...gle.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-i2c@...r.kernel.org, openbmc@...ts.ozlabs.org,
        linux-arm-kernel@...ts.infradead.org, linux-aspeed@...ts.ozlabs.org
Subject: Re: [PATCH] drivers/i2c-aspeed: avoid invalid memory reference after
 timeout

Hi all,

Any comments?

Thanks,

Heyi

在 2022/1/9 下午9:26, Heyi Guo 写道:
> The memory will be freed by the caller if transfer timeout occurs,
> then it would trigger kernel panic if the peer device responds with
> something after timeout and triggers the interrupt handler of aspeed
> i2c driver.
>
> Set the msgs pointer to NULL to avoid invalid memory reference after
> timeout to fix this potential kernel panic.
>
> Signed-off-by: Heyi Guo <guoheyi@...ux.alibaba.com>
>
> -------
>
> Cc: Brendan Higgins <brendanhiggins@...gle.com>
> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> Cc: Joel Stanley <joel@....id.au>
> Cc: Andrew Jeffery <andrew@...id.au>
> Cc: Philipp Zabel <p.zabel@...gutronix.de>
> Cc: linux-i2c@...r.kernel.org
> Cc: openbmc@...ts.ozlabs.org
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-aspeed@...ts.ozlabs.org
> ---
>   drivers/i2c/busses/i2c-aspeed.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
> index 67e8b97c0c950..3ab0396168680 100644
> --- a/drivers/i2c/busses/i2c-aspeed.c
> +++ b/drivers/i2c/busses/i2c-aspeed.c
> @@ -708,6 +708,11 @@ static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
>   		spin_lock_irqsave(&bus->lock, flags);
>   		if (bus->master_state == ASPEED_I2C_MASTER_PENDING)
>   			bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
> +		/*
> +		 * All the buffers may be freed after returning to caller, so
> +		 * set msgs to NULL to avoid memory reference after freeing.
> +		 */
> +		bus->msgs = NULL;
>   		spin_unlock_irqrestore(&bus->lock, flags);
>   
>   		return -ETIMEDOUT;