On Sep 08 2014 or thereabouts, Andrew Duggan wrote: > On 09/05/2014 06:57 AM, Benjamin Tissoires wrote: > >In the Dell XPS 13 9333, it appears that sometimes the bus get confused > >and corrupts the incoming data. It fills the input report with the > >sentinel value "ff". Synaptics told us that such behavior does not comes > >from the touchpad itself, so we filter out such reports here. > > > >Unfortunately, we can not simply discard the incoming data because they > >may contain useful information. Most of the time, the misbehavior is > >quite near the end of the report, so we can still use the valid part of > >it. > > > >Fixes: > >https://bugzilla.redhat.com/show_bug.cgi?id=1123584 > > > >Signed-off-by: Benjamin Tissoires <benjamin.tissoi...@redhat.com> > >--- > > drivers/hid/hid-rmi.c | 31 ++++++++++++++++++++++++++----- > > 1 file changed, 26 insertions(+), 5 deletions(-) > > > >diff --git a/drivers/hid/hid-rmi.c b/drivers/hid/hid-rmi.c > >index 8389e81..db92c3b 100644 > >--- a/drivers/hid/hid-rmi.c > >+++ b/drivers/hid/hid-rmi.c > >@@ -320,9 +320,6 @@ static int rmi_f11_input_event(struct hid_device *hdev, > >u8 irq, u8 *data, > > int offset; > > int i; > >- if (size < hdata->f11.report_size) > >- return 0; > >- > > if (!(irq & hdata->f11.irq_mask)) > > return 0; > >@@ -332,9 +329,13 @@ static int rmi_f11_input_event(struct hid_device *hdev, > >u8 irq, u8 *data, > > int fs_bit_position = (i & 0x3) << 1; > > int finger_state = (data[fs_byte_position] >> fs_bit_position) & > > 0x03; > >+ int position = offset + 5 * i; > >+ > >+ if (position + 5 > size) > >+ /* partial report, go on with what we received */ > >+ break; > >- rmi_f11_process_touch(hdata, i, finger_state, > >- &data[offset + 5 * i]); > >+ rmi_f11_process_touch(hdata, i, finger_state, &data[position]); > > } > > input_mt_sync_frame(hdata->input); > > input_sync(hdata->input); > >@@ -412,9 +413,29 @@ static int rmi_read_data_event(struct hid_device *hdev, > >u8 *data, int size) > > return 1; > > } > >+static int rmi_check_sanity(struct hid_device *hdev, u8 *data, int size) > >+{ > >+ int valid_size = size; > >+ /* > >+ * On the Dell XPS 13 9333, the bus sometimes get confused and fills > >+ * the report with a sentinel value "ff". Synaptics told us that such > >+ * behavior does not comes from the touchpad itself, so we filter out > >+ * such reports here. > >+ */ > >+ > >+ while ((data[valid_size - 1] == 0xff) && valid_size > 0) > >+ valid_size--; > >+ > >+ return valid_size; > >+} > >+ > > static int rmi_raw_event(struct hid_device *hdev, > > struct hid_report *report, u8 *data, int size) > > { > >+ size = rmi_check_sanity(hdev, data, size); > >+ if (size < 2) > >+ return 0; > >+ > > switch (data[0]) { > > case RMI_READ_DATA_REPORT_ID: > > return rmi_read_data_event(hdev, data, size); > I think there should also be a check in rmi_f30_input_event to make sure > that the F30 data is also valid. The F30 data is at the end of the HID > report so if the F30 interrupt bit is set, but the value in the report is FF > then there might be some unintended button events. I think checking that > size > 0 would be sufficient to make sure the F30 data is valid.
Yeah :( Actually, I am missing too checks in f11 and f30. If the size is <= 0, then bail out before doing anything. > > Other then that, the sanity check and validation in rmi_f11_input_event look > good to me. > > Andrew -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
