Bugzilla: 1090161
Upstream-status: sent https://patchwork.kernel.org/patch/4055781/
From patchwork Thu Apr 24 22:26:38 2014
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: HID: rmi: do not fetch more than 16 bytes in a query
From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
X-Patchwork-Id: 4055781
Message-Id: <1398378398-24825-1-git-send-email-benjamin.tissoires@redhat.com>
To: Andrew Duggan <aduggan@synaptics.com>,
Christopher Heiny <cheiny@synaptics.com>,
Jiri Kosina <jkosina@suse.cz>, linux-input@vger.kernel.org,
linux-kernel@vger.kernel.org
Date: Thu, 24 Apr 2014 18:26:38 -0400
A firmware bug is present on the XPS Haswell edition which silently
split the request in two responses when the caller ask for a read of
more than 16 bytes.
The FW sends the first 16 then the 4 next, but it says that it answered
the 20 bytes in the first report.
This occurs only on the retrieving of the min/max of X and Y of the F11
function.
We only use the first 10 bytes of the Ctrl register, so we can get only
those 10 bytes to prevent the bug from happening.
Resolves:
https://bugzilla.redhat.com/show_bug.cgi?id=1090161
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
---
drivers/hid/hid-rmi.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/hid/hid-rmi.c b/drivers/hid/hid-rmi.c
index 7da9509..cee89c9 100644
--- a/drivers/hid/hid-rmi.c
+++ b/drivers/hid/hid-rmi.c
@@ -613,10 +613,15 @@ static int rmi_populate_f11(struct hid_device *hdev)
}
}
- /* retrieve the ctrl registers */
- ret = rmi_read_block(hdev, data->f11.control_base_addr, buf, 20);
+ /*
+ * retrieve the ctrl registers
+ * the ctrl register has a size of 20 but a fw bug split it into 16 + 4,
+ * and there is no way to know if the first 20 bytes are here or not.
+ * We use only the first 10 bytes, so get only them.
+ */
+ ret = rmi_read_block(hdev, data->f11.control_base_addr, buf, 10);
if (ret) {
- hid_err(hdev, "can not read ctrl block of size 20: %d.\n", ret);
+ hid_err(hdev, "can not read ctrl block of size 10: %d.\n", ret);
return ret;
}