From 2ac97f0f6654da14312d125005c77a6010e0ea38 Mon Sep 17 00:00:00 2001 From: Jason Gerecke Date: Tue, 25 Apr 2017 11:29:56 -0700 Subject: [PATCH] HID: wacom: Have wacom_tpc_irq guard against possible NULL dereference The following Smatch complaint was generated in response to commit 2a6cdbd ("HID: wacom: Introduce new 'touch_input' device"): drivers/hid/wacom_wac.c:1586 wacom_tpc_irq() error: we previously assumed 'wacom->touch_input' could be null (see line 1577) The 'touch_input' and 'pen_input' variables point to the 'struct input_dev' used for relaying touch and pen events to userspace, respectively. If a device does not have a touch interface or pen interface, the associated input variable is NULL. The 'wacom_tpc_irq()' function is responsible for forwarding input reports to a more-specific IRQ handler function. An unknown report could theoretically be mistaken as e.g. a touch report on a device which does not have a touch interface. This can be prevented by only calling the pen/touch functions are called when the pen/touch pointers are valid. Fixes: 2a6cdbd ("HID: wacom: Introduce new 'touch_input' device") Signed-off-by: Jason Gerecke Reviewed-by: Ping Cheng Cc: stable@vger.kernel.org Signed-off-by: Jiri Kosina --- drivers/hid/wacom_wac.c | 45 +++++++++++++++++++++-------------------- 1 file changed, 23 insertions(+), 22 deletions(-) diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c index 4b225fb19a16..e274c9dc32f3 100644 --- a/drivers/hid/wacom_wac.c +++ b/drivers/hid/wacom_wac.c @@ -1571,37 +1571,38 @@ static int wacom_tpc_irq(struct wacom_wac *wacom, size_t len) { unsigned char *data = wacom->data; - if (wacom->pen_input) + if (wacom->pen_input) { dev_dbg(wacom->pen_input->dev.parent, "%s: received report #%d\n", __func__, data[0]); - else if (wacom->touch_input) + + if (len == WACOM_PKGLEN_PENABLED || + data[0] == WACOM_REPORT_PENABLED) + return wacom_tpc_pen(wacom); + } + else if (wacom->touch_input) { dev_dbg(wacom->touch_input->dev.parent, "%s: received report #%d\n", __func__, data[0]); - switch (len) { - case WACOM_PKGLEN_TPC1FG: - return wacom_tpc_single_touch(wacom, len); + switch (len) { + case WACOM_PKGLEN_TPC1FG: + return wacom_tpc_single_touch(wacom, len); - case WACOM_PKGLEN_TPC2FG: - return wacom_tpc_mt_touch(wacom); + case WACOM_PKGLEN_TPC2FG: + return wacom_tpc_mt_touch(wacom); - case WACOM_PKGLEN_PENABLED: - return wacom_tpc_pen(wacom); + default: + switch (data[0]) { + case WACOM_REPORT_TPC1FG: + case WACOM_REPORT_TPCHID: + case WACOM_REPORT_TPCST: + case WACOM_REPORT_TPC1FGE: + return wacom_tpc_single_touch(wacom, len); - default: - switch (data[0]) { - case WACOM_REPORT_TPC1FG: - case WACOM_REPORT_TPCHID: - case WACOM_REPORT_TPCST: - case WACOM_REPORT_TPC1FGE: - return wacom_tpc_single_touch(wacom, len); - - case WACOM_REPORT_TPCMT: - case WACOM_REPORT_TPCMT2: - return wacom_mt_touch(wacom); + case WACOM_REPORT_TPCMT: + case WACOM_REPORT_TPCMT2: + return wacom_mt_touch(wacom); - case WACOM_REPORT_PENABLED: - return wacom_tpc_pen(wacom); + } } } -- 2.30.2