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SubjectRe: [PATCH v2] HID: rmi: check that report ids exist in the report_id_hash before accessing their size
On Jul 17 2014 or thereabouts, Andrew Duggan wrote:
> It is possible that the hid-rmi driver could get loaded onto a device which does not have the
> expected report ids. This should not happen because it would indicate that the hid-rmi driver is
> not compatible with that device. However, if it does happen it should return an error from probe
> instead of dereferencing a null pointer.
>
> related bug:
> https://bugzilla.kernel.org/show_bug.cgi?id=80091
>
> Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
> ---
> Added hid_err messages as suggested by Benjamin. This fixes the null pointer dereference from
> bug 80091 while the next patch addresses the binding issue in hid-core.

Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Cheers,
Benjamin

>
> drivers/hid/hid-rmi.c | 28 ++++++++++++++++++++++------
> 1 file changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hid/hid-rmi.c b/drivers/hid/hid-rmi.c
> index 3221a95..260be7a 100644
> --- a/drivers/hid/hid-rmi.c
> +++ b/drivers/hid/hid-rmi.c
> @@ -848,6 +848,8 @@ static int rmi_probe(struct hid_device *hdev, const struct hid_device_id *id)
> struct rmi_data *data = NULL;
> int ret;
> size_t alloc_size;
> + struct hid_report *input_report;
> + struct hid_report *output_report;
>
> data = devm_kzalloc(&hdev->dev, sizeof(struct rmi_data), GFP_KERNEL);
> if (!data)
> @@ -866,12 +868,26 @@ static int rmi_probe(struct hid_device *hdev, const struct hid_device_id *id)
> return ret;
> }
>
> - data->input_report_size = (hdev->report_enum[HID_INPUT_REPORT]
> - .report_id_hash[RMI_ATTN_REPORT_ID]->size >> 3)
> - + 1 /* report id */;
> - data->output_report_size = (hdev->report_enum[HID_OUTPUT_REPORT]
> - .report_id_hash[RMI_WRITE_REPORT_ID]->size >> 3)
> - + 1 /* report id */;
> + input_report = hdev->report_enum[HID_INPUT_REPORT]
> + .report_id_hash[RMI_ATTN_REPORT_ID];
> + if (!input_report) {
> + hid_err(hdev, "device does not have expected input report\n");
> + ret = -ENODEV;
> + return ret;
> + }
> +
> + data->input_report_size = (input_report->size >> 3) + 1 /* report id */;
> +
> + output_report = hdev->report_enum[HID_OUTPUT_REPORT]
> + .report_id_hash[RMI_WRITE_REPORT_ID];
> + if (!output_report) {
> + hid_err(hdev, "device does not have expected output report\n");
> + ret = -ENODEV;
> + return ret;
> + }
> +
> + data->output_report_size = (output_report->size >> 3)
> + + 1 /* report id */;
>
> alloc_size = data->output_report_size + data->input_report_size;
>
> --
> 1.9.1
>


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