linux-kernel - Re: [PATCH v1] i2c: aspeed: fixed potential null pointer dereference

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Date:   Mon, 31 Jul 2017 18:57:09 +0930
From:   Joel Stanley <joel@....id.au>
To:     Brendan Higgins <brendanhiggins@...gle.com>
Cc:     Wolfram Sang <wsa@...-dreams.de>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Patrick Venture <venture@...gle.com>,
        linux-i2c@...r.kernel.org,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] i2c: aspeed: fixed potential null pointer dereference

On Sat, Jul 29, 2017 at 10:30 AM, Brendan Higgins
<brendanhiggins@...gle.com> wrote:
> Before I skipped null checks when the master is in the STOP state; this
> fixes that.
>
> Signed-off-by: Brendan Higgins <brendanhiggins@...gle.com>

Acked-by: Joel Stanley <joel@....id.au>

Out of interest, was this found by code review, or did you hit this in testing?

Cheers,

Joel

> ---
>  drivers/i2c/busses/i2c-aspeed.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
> index f19348328a71..6fdf9231c23c 100644
> --- a/drivers/i2c/busses/i2c-aspeed.c
> +++ b/drivers/i2c/busses/i2c-aspeed.c
> @@ -410,10 +410,11 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>         }
>
>         /* We are in an invalid state; reset bus to a known state. */
> -       if (!bus->msgs && bus->master_state != ASPEED_I2C_MASTER_STOP) {
> +       if (!bus->msgs) {
>                 dev_err(bus->dev, "bus in unknown state");
>                 bus->cmd_err = -EIO;
> -               aspeed_i2c_do_stop(bus);
> +               if (bus->master_state != ASPEED_I2C_MASTER_STOP)
> +                       aspeed_i2c_do_stop(bus);
>                 goto out_no_complete;
>         }
>         msg = &bus->msgs[bus->msgs_index];
> --
> 2.14.0.rc0.400.g1c36432dff-goog
>