Fix wacom touchscreens (rhbz 1918486)

Signed-off-by: Justin M. Forbes <jforbes@fedoraproject.org>

2 files changed, 89 insertions, 0 deletions

diff --git a/hid-wacom-correct-null-dereference-on-aes-pen-proximity.patch b/hid-wacom-correct-null-dereference-on-aes-pen-proximity.patch
new file mode 100644
index 000000000..d76b6489b
--- /dev/null
+++ b/hid-wacom-correct-null-dereference-on-aes-pen-proximity.patch
@@ -0,0 +1,85 @@
+From MAILER-DAEMON Wed Jan 27 14:42:50 2021
+From: Jason Gerecke <killertofu@gmail.com>
+To: linux-input@vger.kernel.org, Jiri Kosina <jikos@kernel.org>, Benjamin Tissoires <benjamin.tissoires@redhat.com>
+Cc: Jason Gerecke <jason.gerecke@wacom.com>, stable@vger.kernel.org, Ping Cheng <ping.cheng@wacom.com>
+Subject: [PATCH] HID: wacom: Correct NULL dereference on AES pen proximity
+Date: Thu, 21 Jan 2021 10:46:49 -0800
+Message-Id: <20210121184649.157189-1-jason.gerecke@wacom.com>
+List-ID: <linux-input.vger.kernel.org>
+X-Mailing-List: linux-input@vger.kernel.org
+MIME-Version: 1.0
+Content-Type: text/plain; charset="utf-8"
+Content-Transfer-Encoding: 7bit
+
+The recent commit to fix a memory leak introduced an inadvertant NULL
+pointer dereference. The `wacom_wac->pen_fifo` variable was never
+intialized, resuling in a crash whenever functions tried to use it.
+Since the FIFO is only used by AES pens (to buffer events from pen
+proximity until the hardware reports the pen serial number) this would
+have been easily overlooked without testing an AES device.
+
+This patch converts `wacom_wac->pen_fifo` over to a pointer (since the
+call to `devres_alloc` allocates memory for us) and ensures that we assign
+it to point to the allocated and initalized `pen_fifo` before the function
+returns.
+
+Fixes: 37309f47e2f5 ("HID: wacom: Fix memory leakage caused by kfifo_alloc")
+Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
+Tested-by: Ping Cheng <ping.cheng@wacom.com>
+CC: stable@vger.kernel.org # v4.19+
+Link: https://github.com/linuxwacom/input-wacom/issues/230
+---
+ drivers/hid/wacom_sys.c | 7 ++++---
+ drivers/hid/wacom_wac.h | 2 +-
+ 2 files changed, 5 insertions(+), 4 deletions(-)
+
+diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
+index e8acd235db2a..aa9e48876ced 100644
+--- a/drivers/hid/wacom_sys.c
++++ b/drivers/hid/wacom_sys.c
+@@ -147,9 +147,9 @@ static int wacom_wac_pen_serial_enforce(struct hid_device *hdev,
+ 	}
+ 
+ 	if (flush)
+-		wacom_wac_queue_flush(hdev, &wacom_wac->pen_fifo);
++		wacom_wac_queue_flush(hdev, wacom_wac->pen_fifo);
+ 	else if (insert)
+-		wacom_wac_queue_insert(hdev, &wacom_wac->pen_fifo,
++		wacom_wac_queue_insert(hdev, wacom_wac->pen_fifo,
+ 				       raw_data, report_size);
+ 
+ 	return insert && !flush;
+@@ -1280,7 +1280,7 @@ static void wacom_devm_kfifo_release(struct device *dev, void *res)
+ static int wacom_devm_kfifo_alloc(struct wacom *wacom)
+ {
+ 	struct wacom_wac *wacom_wac = &wacom->wacom_wac;
+-	struct kfifo_rec_ptr_2 *pen_fifo = &wacom_wac->pen_fifo;
++	struct kfifo_rec_ptr_2 *pen_fifo;
+ 	int error;
+ 
+ 	pen_fifo = devres_alloc(wacom_devm_kfifo_release,
+@@ -1297,6 +1297,7 @@ static int wacom_devm_kfifo_alloc(struct wacom *wacom)
+ 	}
+ 
+ 	devres_add(&wacom->hdev->dev, pen_fifo);
++	wacom_wac->pen_fifo = pen_fifo;
+ 
+ 	return 0;
+ }
+diff --git a/drivers/hid/wacom_wac.h b/drivers/hid/wacom_wac.h
+index da612b6e9c77..195910dd2154 100644
+--- a/drivers/hid/wacom_wac.h
++++ b/drivers/hid/wacom_wac.h
+@@ -342,7 +342,7 @@ struct wacom_wac {
+ 	struct input_dev *pen_input;
+ 	struct input_dev *touch_input;
+ 	struct input_dev *pad_input;
+-	struct kfifo_rec_ptr_2 pen_fifo;
++	struct kfifo_rec_ptr_2 *pen_fifo;
+ 	int pid;
+ 	int num_contacts_left;
+ 	u8 bt_features;
+-- 
+2.30.0
+
+
diff --git a/kernel.spec b/kernel.spec
index d2c6ebf0e..9a00a5dec 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -855,6 +855,9 @@ Patch107: 0001-drm-nouveau-kms-handle-mDP-connectors.patch
 # rhbz 1918778
 Patch108: media-pwc-fix-the-urb-buffer-allocation.patch
 
+#rhbz 1918486
+Patch109: hid-wacom-correct-null-dereference-on-aes-pen-proximity.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -2971,6 +2974,7 @@ fi
 * Wed Jan 27 08:07:52 CST 2021 Justin M. Forbes <jforbes@fedoraproject.org> - 5.10.11-100
 - Linux v5.10.11
 - Fix URB buffer allocation of pwc driver (rhbz 1918778)
+- Fix wacom touchscreens (rhbz 1918486)
 
 * Sun Jan 24 11:29:01 CST 2021 Justin M. Forbes <jforbes@fedoraproject.org> - 5.10.10-100
 - Linux v5.10.10