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[PATCH 4.4 21/29] HID: wacom: Fix poor prox handling in wacom_pl_irq

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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jason Gerecke <killertofu@gmail.com>

commit 282e4637bc1c0b338708bcebd09d31c69abec070 upstream.

Commit 025bcc1 performed cleanup work on the 'wacom_pl_irq' function, making
it follow the standards used in the rest of the codebase. The change
unintiontionally allowed the function to send input events from reports
that are not marked as being in prox. This can cause problems as the
report values for X, Y, etc. are not guaranteed to be correct. In
particular, occasionally the tablet will send a report with these values
set to zero. If such a report is received it can caus an unexpected jump
in the XY position.

This patch surrounds more of the processing code with a proximity check,
preventing these zeroed reports from overwriting the current state. To
be safe, only the tool type and ABS_MISC events should be reported when
the pen is marked as being out of prox.

Fixes: 025bcc1540 ("HID: wacom: Simplify 'wacom_pl_irq'")
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/hid/wacom_wac.c |   24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -148,19 +148,21 @@ static int wacom_pl_irq(struct wacom_wac
 		wacom->id[0] = STYLUS_DEVICE_ID;
 	}
 
-	pressure = (signed char)((data[7] << 1) | ((data[4] >> 2) & 1));
-	if (features->pressure_max > 255)
-		pressure = (pressure << 1) | ((data[4] >> 6) & 1);
-	pressure += (features->pressure_max + 1) / 2;
+	if (prox) {
+		pressure = (signed char)((data[7] << 1) | ((data[4] >> 2) & 1));
+		if (features->pressure_max > 255)
+			pressure = (pressure << 1) | ((data[4] >> 6) & 1);
+		pressure += (features->pressure_max + 1) / 2;
 
-	input_report_abs(input, ABS_X, data[3] | (data[2] << 7) | ((data[1] & 0x03) << 14));
-	input_report_abs(input, ABS_Y, data[6] | (data[5] << 7) | ((data[4] & 0x03) << 14));
-	input_report_abs(input, ABS_PRESSURE, pressure);
+		input_report_abs(input, ABS_X, data[3] | (data[2] << 7) | ((data[1] & 0x03) << 14));
+		input_report_abs(input, ABS_Y, data[6] | (data[5] << 7) | ((data[4] & 0x03) << 14));
+		input_report_abs(input, ABS_PRESSURE, pressure);
 
-	input_report_key(input, BTN_TOUCH, data[4] & 0x08);
-	input_report_key(input, BTN_STYLUS, data[4] & 0x10);
-	/* Only allow the stylus2 button to be reported for the pen tool. */
-	input_report_key(input, BTN_STYLUS2, (wacom->tool[0] == BTN_TOOL_PEN) && (data[4] & 0x20));
+		input_report_key(input, BTN_TOUCH, data[4] & 0x08);
+		input_report_key(input, BTN_STYLUS, data[4] & 0x10);
+		/* Only allow the stylus2 button to be reported for the pen tool. */
+		input_report_key(input, BTN_STYLUS2, (wacom->tool[0] == BTN_TOOL_PEN) && (data[4] & 0x20));
+	}
 
 	if (!prox)
 		wacom->id[0] = 0;

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[PATCH 4.4 00/29] 4.4.48-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 23/29] USB: serial: qcserial: add Dell DW5570 QDL Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 13/29] svcrpc: fix oops in absence of krb5 module Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 07/29] perf/core: Fix PERF_RECORD_MMAP2 prot/flags for anonymous memory Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 29/29] base/memory, hotplug: fix a kernel oops in show_valid_zones() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 20/29] percpu-refcount: fix reference leak during percpu-atomic transition Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 18/29] can: bcm: fix hrtimer/tasklet termination in bcm op removal Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 24/29] USB: serial: pl2303: add ATEN device ID Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 08/29] ata: sata_mv:- Handle return value of devm_ioremap. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 11/29] powerpc: Add missing error check to prom_find_boot_cpu() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 21/29] HID: wacom: Fix poor prox handling in wacom_pl_irq Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 03/29] drm/nouveau/disp/gt215: Fix HDA ELD handling (thus, HDMI audio) on gt215 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 28/29] x86/irq: Make irq activate operations symmetric Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 02/29] ext4: validate s_first_meta_bg at mount time Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 15/29] cifs: initialize file_info_lock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 26/29] usb: gadget: f_fs: Assorted buffer overflow checks. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 04/29] drm/nouveau/nv1a,nv1f/disp: fix memory clock rate retrieval Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 13:50 +0100
  [PATCH 4.4 01/29] PCI/ASPM: Handle PCI-to-PCIe bridges as roots of PCIe hierarchies Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 14:00 +0100
  [PATCH 4.4 14/29] zswap: disable changing params if init fails Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 14:00 +0100
  [PATCH 4.4 16/29] mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 14:00 +0100
  [PATCH 4.4 12/29] NFSD: Fix a null reference case in find_or_create_lock_stateid() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 14:00 +0100
  [PATCH 4.4 19/29] mmc: sdhci: Ignore unexpected CARD_INT interrupts Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-07 14:00 +0100
  Re: [PATCH 4.4 00/29] 4.4.48-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-02-07 17:00 +0100
  Re: [PATCH 4.4 00/29] 4.4.48-stable review Guenter Roeck <linux@roeck-us.net> - 2017-02-07 22:50 +0100
  Re: [PATCH 4.4 00/29] 4.4.48-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-08 07:40 +0100
    Re: [PATCH 4.4 00/29] 4.4.48-stable review Kevin Hilman <khilman@baylibre.com> - 2017-02-08 20:50 +0100
      Re: [PATCH 4.4 00/29] 4.4.48-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-08 21:10 +0100

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