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SubjectRe: [PATCH v2] bus: hisi_lpc: Don't use devm_kzalloc() to allocate logical PIO range
[+cc Zhichang, logic_pio author]

On Fri, Jun 14, 2019 at 5:26 AM John Garry <john.garry@huawei.com> wrote:
>
> If, after registering a logical PIO range, the driver probe later fails,
> the logical PIO range memory will be released automatically.
>
> This causes an issue, in that the logical PIO range is not unregistered
> (that is not supported) and the released range memory may be later
> referenced
>
> Allocate the logical PIO range with kzalloc() to avoid this potential
> issue.
>
> Fixes: adf38bb0b5956 ("HISI LPC: Support the LPC host on Hip06/Hip07 with DT bindings")
> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
>
> Change to v1:
> - add comment, as advised by Joe Perches
>
> diff --git a/drivers/bus/hisi_lpc.c b/drivers/bus/hisi_lpc.c
> index 19d7b6ff2f17..5f0130a693fe 100644
> --- a/drivers/bus/hisi_lpc.c
> +++ b/drivers/bus/hisi_lpc.c
> @@ -599,7 +599,8 @@ static int hisi_lpc_probe(struct platform_device *pdev)
> if (IS_ERR(lpcdev->membase))
> return PTR_ERR(lpcdev->membase);
>
> - range = devm_kzalloc(dev, sizeof(*range), GFP_KERNEL);
> + /* Logical PIO may reference 'range' memory even if the probe fails */
> + range = kzalloc(sizeof(*range), GFP_KERNEL);

This doesn't feel like the correct way to fix this. If the probe
fails, everything done by the probe should be undone, including the
allocation and registration of "range". I don't know what the best
mechanism is, but I'm skeptical about this one.

> if (!range)
> return -ENOMEM;
>
> @@ -610,6 +611,7 @@ static int hisi_lpc_probe(struct platform_device *pdev)
> ret = logic_pio_register_range(range);
> if (ret) {
> dev_err(dev, "register IO range failed (%d)!\n", ret);
> + kfree(range);
> return ret;
> }
> lpcdev->io_host = range;
> --
> 2.17.1
>

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