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SubjectRe: [bug report] Input: add st-keyscan driver
On Sat, Jan 26, 2019 at 1:25 PM Ken Sloat
<ken.sloat@ohmlinxelectronics.com> wrote:
>
> On Tue, Jan 22, 2019 at 1:53 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> >
> > Hello Gabriel FERNANDEZ,
>
> Hello Dan,
>
> I have added CCs for the maintainers as well as Gabriel Fernandez as
> currently you just have the linux-input mailing list
>
> > The patch 062589b13991: "Input: add st-keyscan driver" from Apr 12,
> > 2014, leads to the following static checker warning:
> >
> > drivers/input/keyboard/st-keyscan.c:156 keyscan_probe()
> > error: potential zalloc NULL dereference: 'keypad_data->input_dev'
> >
> > drivers/input/keyboard/st-keyscan.c
> > 125 static int keyscan_probe(struct platform_device *pdev)
> > 126 {
> > 127 struct st_keyscan *keypad_data;
> > 128 struct input_dev *input_dev;
> > 129 struct resource *res;
> > 130 int error;
> > 131
> > 132 if (!pdev->dev.of_node) {
> > 133 dev_err(&pdev->dev, "no DT data present\n");
> > 134 return -EINVAL;
> > 135 }
> > 136
> > 137 keypad_data = devm_kzalloc(&pdev->dev, sizeof(*keypad_data),
> > 138 GFP_KERNEL);
> > 139 if (!keypad_data)
> > 140 return -ENOMEM;
> > 141
> > 142 input_dev = devm_input_allocate_device(&pdev->dev);
> > 143 if (!input_dev) {
> > 144 dev_err(&pdev->dev, "failed to allocate the input device\n");
> > 145 return -ENOMEM;
> > 146 }
> > 147
> > 148 input_dev->name = pdev->name;
> > 149 input_dev->phys = "keyscan-keys/input0";
> > 150 input_dev->dev.parent = &pdev->dev;
> > 151 input_dev->open = keyscan_open;
> > 152 input_dev->close = keyscan_close;
> > 153
> > 154 input_dev->id.bustype = BUS_HOST;
> > 155
> > --> 156 error = keypad_matrix_key_parse_dt(keypad_data);
> > ^^^^^^^^^^^
> I agree with you this would be a problem
> to clarify the NULL derefence would occur here within keypad_matrix_key_parse_dt
>
> struct device *dev = keypad_data->input_dev->dev.parent;
>
> > This assumes we have set "keypad_data->input_dev = input_dev;" but we
> > don't do that until...
> >
> > 157 if (error)
> > 158 return error;
> > 159
> > 160 error = matrix_keypad_build_keymap(NULL, NULL,
> > 161 keypad_data->n_rows,
> > 162 keypad_data->n_cols,
> > 163 NULL, input_dev);
> > 164 if (error) {
> > 165 dev_err(&pdev->dev, "failed to build keymap\n");
> > 166 return error;
> > 167 }
> > 168
> > 169 input_set_drvdata(input_dev, keypad_data);
> > 170
> > 171 keypad_data->input_dev = input_dev;
> > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >
> > this line here. This driver has never worked and it was included almost
> > five years ago. Is it worth fixing?
> >
> > 172
> > 173 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > 174 keypad_data->base = devm_ioremap_resource(&pdev->dev, res);
> > 175 if (IS_ERR(keypad_data->base))
> > 176 return PTR_ERR(keypad_data->base);
> > 177
> >
> > regards,
> > dan carpenter
> >
>
> Here is the interesting thing, I was looking on patchwork, and several
> of the patches including what appears to be the latest actually set
> "keypad_data->input_dev = input_dev" before calling
> "keypad_matrix_key_parse_dt"
>
> From v4 on patchwork
> + if (IS_ERR(keypad_data->clk)) {
> + dev_err(&pdev->dev, "cannot get clock");
> + return PTR_ERR(keypad_data->clk);
> + }
> +
> + keypad_data->input_dev = input_dev;
> +
> + input_dev->name = pdev->name;
> + input_dev->phys = "keyscan-keys/input0";
> + input_dev->dev.parent = &pdev->dev;
> + input_dev->open = keyscan_open;
> + input_dev->close = keyscan_close;
> +
> + input_dev->id.bustype = BUS_HOST;
> +
> + error = keypad_matrix_key_parse_dt(keypad_data);
>
> According to patchwork, these aren't listed as accepted, so I'm not
> sure where the exact accepted patch came from. Looking at the commit
> log, it looks like the issue you showed above was made in the original
> commit 062589b1399176a9c14bc68e16169f40439d658c so I'm not quite sure
> what is going on here. Maybe the maintainer can chime in with the
> original patch/mailing list discussion on this. For reference, I've
> added the patchwork links below
> https://patchwork.kernel.org/patch/3854341/
> https://patchwork.kernel.org/patch/3968891/
> https://patchwork.kernel.org/patch/3969991/

It may very well be that I messed up when applying the patch. I guess
whatever platform that is using the driver has not attempted to update
their kernel since then.

Thanks.

--
Dmitry

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