[PATCH] Input: wacom_w8001 - Ignore bogus idx values in interrupt

Subsystems: input (keyboard, mouse, joystick, touchscreen) drivers, the rest

STALE3768d

4 messages, 3 authors, 2016-05-23 · open the first message on its own page

[PATCH] Input: wacom_w8001 - Ignore bogus idx values in interrupt

From: Chris J Arges <hidden>
Date: 2016-05-23 01:42:31

I've noticed crashes when using my x60t using a coreboot bios. When using
the pen I can produce a crash simply by tapping a few times. This
generates an event which has an idx of 0xc. This in turn crashes the
machine because the array access is greater than W8001_MAX_LENGTH. This
patch checks for bogus values and filters them in order to prevent crashes.

Signed-off-by: Chris J Arges <redacted>
---
 drivers/input/touchscreen/wacom_w8001.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/input/touchscreen/wacom_w8001.c b/drivers/input/touchscreen/wacom_w8001.c
index bab3c6a..c858200 100644
--- a/drivers/input/touchscreen/wacom_w8001.c
+++ b/drivers/input/touchscreen/wacom_w8001.c

@@ -283,6 +283,15 @@ static irqreturn_t w8001_interrupt(struct serio *serio,
 	unsigned char tmp;
 
 	w8001->data[w8001->idx] = data;
+
+	/* ignore bogus idx values */
+	if (w8001->idx >= W8001_MAX_LENGTH) {
+		pr_info("w8001: ignored interrupt: data 0x%02x idx %d\n", data,
+			w8001->idx);
+		w8001->idx = 0;
+		return IRQ_HANDLED;
+	}
+
 	switch (w8001->idx++) {
 	case 0:
 		if ((data & W8001_LEAD_MASK) != W8001_LEAD_BYTE) {

-- 
2.7.4

Re: [PATCH] Input: wacom_w8001 - Ignore bogus idx values in interrupt

From: Ping Cheng <hidden>
Date: 2016-05-23 05:22:09

Hi Chris,

On Sun, May 22, 2016 at 6:42 PM, Chris J Arges
[off-list ref] wrote:

I've noticed crashes when using my x60t using a coreboot bios. When using
the pen I can produce a crash simply by tapping a few times. This
generates an event which has an idx of 0xc. This in turn crashes the
machine because the array access is greater than W8001_MAX_LENGTH. This
patch checks for bogus values and filters them in order to prevent crashes.

Thank you for submitting a patch in addition to reporting the issue.

quoted hunk

Signed-off-by: Chris J Arges <redacted>
---
 drivers/input/touchscreen/wacom_w8001.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/input/touchscreen/wacom_w8001.c b/drivers/input/touchscreen/wacom_w8001.c
index bab3c6a..c858200 100644
--- a/drivers/input/touchscreen/wacom_w8001.c
+++ b/drivers/input/touchscreen/wacom_w8001.c

@@ -283,6 +283,15 @@ static irqreturn_t w8001_interrupt(struct serio *serio,
        unsigned char tmp;

        w8001->data[w8001->idx] = data;
+
+       /* ignore bogus idx values */
+       if (w8001->idx >= W8001_MAX_LENGTH) {
+               pr_info("w8001: ignored interrupt: data 0x%02x idx %d\n", data,
+                       w8001->idx);
+               w8001->idx = 0;
+               return IRQ_HANDLED;
+       }
+

I don't have an x60t system to test with. I wonder if your system
supports two finger touch or not. We at least have a bug in the code
since W8001_MAX_LENGTH should be 13 instead of 11. How come no one had
encountered that issue before?

I'm going to email a patch to the list. Please test it and let us know
your result. Maybe we still need your patch if your device doesn't
support two finger touch or the idx=0xc can't be fixed by
W8001_MAX_LENGTH=13.

Thanks,

Ping

        switch (w8001->idx++) {
        case 0:
                if ((data & W8001_LEAD_MASK) != W8001_LEAD_BYTE) {
--
2.7.4

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Re: [PATCH] Input: wacom_w8001 - Ignore bogus idx values in interrupt

From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: 2016-05-23 16:52:33

On Sun, May 22, 2016 at 10:21:45PM -0700, Ping Cheng wrote:

Hi Chris,

On Sun, May 22, 2016 at 6:42 PM, Chris J Arges
[off-list ref] wrote:

quoted

I've noticed crashes when using my x60t using a coreboot bios. When using
the pen I can produce a crash simply by tapping a few times. This
generates an event which has an idx of 0xc. This in turn crashes the
machine because the array access is greater than W8001_MAX_LENGTH. This
patch checks for bogus values and filters them in order to prevent crashes.

Thank you for submitting a patch in addition to reporting the issue.

quoted

Signed-off-by: Chris J Arges <redacted>
---
 drivers/input/touchscreen/wacom_w8001.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/input/touchscreen/wacom_w8001.c b/drivers/input/touchscreen/wacom_w8001.c
index bab3c6a..c858200 100644
--- a/drivers/input/touchscreen/wacom_w8001.c
+++ b/drivers/input/touchscreen/wacom_w8001.c

@@ -283,6 +283,15 @@ static irqreturn_t w8001_interrupt(struct serio *serio,
        unsigned char tmp;

        w8001->data[w8001->idx] = data;
+
+       /* ignore bogus idx values */
+       if (w8001->idx >= W8001_MAX_LENGTH) {
+               pr_info("w8001: ignored interrupt: data 0x%02x idx %d\n", data,
+                       w8001->idx);
+               w8001->idx = 0;
+               return IRQ_HANDLED;
+       }
+

I don't have an x60t system to test with. I wonder if your system
supports two finger touch or not. We at least have a bug in the code
since W8001_MAX_LENGTH should be 13 instead of 11. How come no one had
encountered that issue before?

I'm going to email a patch to the list. Please test it and let us know
your result. Maybe we still need your patch if your device doesn't
support two finger touch or the idx=0xc can't be fixed by
W8001_MAX_LENGTH=13.

Just so we are clear this version of the patch is buggy as we check the
index only after [potentially] writing past the array bounds of
w8001->data[].

Thanks.

-- 
Dmitry

Re: [PATCH] Input: wacom_w8001 - Ignore bogus idx values in interrupt

From: Ping Cheng <hidden>
Date: 2016-05-23 18:01:07

On Mon, May 23, 2016 at 9:52 AM, Dmitry Torokhov
[off-list ref] wrote:

On Sun, May 22, 2016 at 10:21:45PM -0700, Ping Cheng wrote:

quoted

Hi Chris,

On Sun, May 22, 2016 at 6:42 PM, Chris J Arges
[off-list ref] wrote:

quoted

I've noticed crashes when using my x60t using a coreboot bios. When using
the pen I can produce a crash simply by tapping a few times. This
generates an event which has an idx of 0xc. This in turn crashes the
machine because the array access is greater than W8001_MAX_LENGTH. This
patch checks for bogus values and filters them in order to prevent crashes.

Thank you for submitting a patch in addition to reporting the issue.

quoted

Signed-off-by: Chris J Arges <redacted>
---
 drivers/input/touchscreen/wacom_w8001.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/input/touchscreen/wacom_w8001.c b/drivers/input/touchscreen/wacom_w8001.c
index bab3c6a..c858200 100644
--- a/drivers/input/touchscreen/wacom_w8001.c
+++ b/drivers/input/touchscreen/wacom_w8001.c

@@ -283,6 +283,15 @@ static irqreturn_t w8001_interrupt(struct serio *serio,
        unsigned char tmp;

        w8001->data[w8001->idx] = data;
+
+       /* ignore bogus idx values */
+       if (w8001->idx >= W8001_MAX_LENGTH) {
+               pr_info("w8001: ignored interrupt: data 0x%02x idx %d\n", data,
+                       w8001->idx);
+               w8001->idx = 0;
+               return IRQ_HANDLED;
+       }
+

I don't have an x60t system to test with. I wonder if your system
supports two finger touch or not. We at least have a bug in the code
since W8001_MAX_LENGTH should be 13 instead of 11. How come no one had
encountered that issue before?

I'm going to email a patch to the list. Please test it and let us know
your result. Maybe we still need your patch if your device doesn't
support two finger touch or the idx=0xc can't be fixed by
W8001_MAX_LENGTH=13.

Just so we are clear this version of the patch is buggy as we check the
index only after [potentially] writing past the array bounds of
w8001->data[].

Thanks for the heads up. I noticed that last night. Since it breaks
two-finger touch, we won't use it anyway.

My other patch is still necessary though. You'll need to change:

From: wacom <redacted>

to

From: Ping Cheng <redacted>

I made it on a brand new system, which I didn't setup the environment
properly. I can update the patch if that's what you like...

Ping

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