[BUG + PATCH] HID ELAN9038 probe fails with "report is too long"

[BUG + PATCH] HID ELAN9038 probe fails with "report is too long"

[js]

[-- Attachment #1: Type: text/plain, Size: 1532 bytes --]

i posted this bug to bugzilla with the attached patch.
this email is to notify the maintainers.
https://bugzilla.kernel.org/show_bug.cgi?id=206259

thanks!

js
----

ELAN i2c digitizer on microsoft surface go fails to initialize and
device is non-functional

initialization fails on 4.19.96:
----
[    5.507245] hid-generic 0018:04F3:261A.0005: report is too long
[    5.507256] hid-generic 0018:04F3:261A.0005: item 0 1 0 8 parsing failed
[    5.507290] hid-generic: probe of 0018:04F3:261A.0005 failed with error -22
[    5.556409] hid-multitouch 0018:04F3:261A.0005: report is too long
[    5.581641] hid-multitouch 0018:04F3:261A.0005: item 0 1 0 8 parsing failed
[    5.618495] hid-multitouch: probe of 0018:04F3:261A.0005 failed
with error -22

initialization succeeds on 4.19.95:
----
[    7.150887] hid-generic 0018:04F3:261A.0001: input,hidraw2: I2C HID
v1.00 Device [ELAN9038:00 04F3:261A] on i2c-ELAN9038:00
[    8.253077] input: ELAN9038:00 04F3:261A as
/devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-1/i2c-ELAN9038:00/0018:04F3:261A.0001/input/input20
[    8.253219] input: ELAN9038:00 04F3:261A Pen as
/devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-1/i2c-ELAN9038:00/0018:04F3:261A.0001/input/input23
[    8.253330] hid-multitouch 0018:04F3:261A.0001: input,hidraw0: I2C
HID v1.00 Device [ELAN9038:00 04F3:261A] on i2c-ELAN9038:00

problem seems to be due to this commit:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.19.y&id=31d06cc8e7caec36bedeb4f90444920431462f61

[-- Attachment #2: hid-core.patch --]
[-- Type: text/x-patch, Size: 694 bytes --]

diff -rupN linux-4.19.97/drivers/hid/hid-core.c linux-4.19.97-1/drivers/hid/hid-core.c
--- linux-4.19.97/drivers/hid/hid-core.c	2020-01-17 18:47:17.000000000 +0000
+++ linux-4.19.97-1/drivers/hid/hid-core.c	2020-01-19 16:31:31.823005977 +0000
@@ -290,8 +290,11 @@ static int hid_add_field(struct hid_pars
 
 	/* Total size check: Allow for possible report index byte */
 	if (report->size > (HID_MAX_BUFFER_SIZE - 1) << 3) {
-		hid_err(parser->device, "report is too long\n");
-		return -1;
+		hid_err(parser->device,
+				"report is too long: %d > %d\n",
+				report->size,
+				(HID_MAX_BUFFER_SIZE - 1) << 3);
+		return 0;
 	}
 
 	if (!parser->local.usage_index) /* Ignore padding fields */

Re: [BUG + PATCH] HID ELAN9038 probe fails with "report is too long"

[js]

i'm bumping this bug because i haven't heard anything from the
maintainers for a week.
there's been no change in the git either.
what's going on guys? this is a tiny patch for a very simple bug.
it should be a fast review and commit to the kernel tree.

js

On Sun, Jan 19, 2020 at 1:14 PM js <sym.i.nem@gmail.com> wrote:
>
> i posted this bug to bugzilla with the attached patch.
> this email is to notify the maintainers.
> https://bugzilla.kernel.org/show_bug.cgi?id=206259
>
> thanks!
>
> js
> ----
>
> ELAN i2c digitizer on microsoft surface go fails to initialize and
> device is non-functional
>
> initialization fails on 4.19.96:
> ----
> [    5.507245] hid-generic 0018:04F3:261A.0005: report is too long
> [    5.507256] hid-generic 0018:04F3:261A.0005: item 0 1 0 8 parsing failed
> [    5.507290] hid-generic: probe of 0018:04F3:261A.0005 failed with error -22
> [    5.556409] hid-multitouch 0018:04F3:261A.0005: report is too long
> [    5.581641] hid-multitouch 0018:04F3:261A.0005: item 0 1 0 8 parsing failed
> [    5.618495] hid-multitouch: probe of 0018:04F3:261A.0005 failed
> with error -22
>
> initialization succeeds on 4.19.95:
> ----
> [    7.150887] hid-generic 0018:04F3:261A.0001: input,hidraw2: I2C HID
> v1.00 Device [ELAN9038:00 04F3:261A] on i2c-ELAN9038:00
> [    8.253077] input: ELAN9038:00 04F3:261A as
> /devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-1/i2c-ELAN9038:00/0018:04F3:261A.0001/input/input20
> [    8.253219] input: ELAN9038:00 04F3:261A Pen as
> /devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-1/i2c-ELAN9038:00/0018:04F3:261A.0001/input/input23
> [    8.253330] hid-multitouch 0018:04F3:261A.0001: input,hidraw0: I2C
> HID v1.00 Device [ELAN9038:00 04F3:261A] on i2c-ELAN9038:00
>
> problem seems to be due to this commit:
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.19.y&id=31d06cc8e7caec36bedeb4f90444920431462f61

Re: [BUG + PATCH] HID ELAN9038 probe fails with "report is too long"

[Benjamin Tissoires]

Hi,

On Mon, Jan 27, 2020 at 9:41 PM js <sym.i.nem@gmail.com> wrote:
>
> i'm bumping this bug because i haven't heard anything from the
> maintainers for a week.

Apologies for the delay. I have been in a conference the past 2 weeks
in Australia, so couldn't handle much of upstream.
Furthermore, we are currently in the merge window, which means we
should not push patches to linux-next unless they are absolutely
needed.

> there's been no change in the git either.
> what's going on guys? this is a tiny patch for a very simple bug.
> it should be a fast review and commit to the kernel tree.

Nope, that is not that simple:

- please submit your patches following
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst#n340
Our tools require the patches to not be attached in an email so we can
process them
- this patch affects the core of the HID subsystem, which means we
should take extra care when dealing with it to not break other systems
- this patch seems to paper over a security patch
(8ec321e96e056de84022c032ffea253431a83c3c) by changing the return
value from an error to "yeah, that's fine". So unless there is a proof
that this is the correct way, it's going to be a nack from me until
proven otherwise
- this patch affects in the end hid-multitouch, and as mentioned in
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/hid/hid-multitouch.c#n26
I'd like to have a reproducer in
https://gitlab.freedesktop.org/libevdev/hid-tools so we do not break
those devices in the future.

So I understand the frustration of having a HW regression, but this
patch is clearly not the correct solution given what I have here, so I
can not push it right now.

Cheers,
Benjamin

>
> js
>
> On Sun, Jan 19, 2020 at 1:14 PM js <sym.i.nem@gmail.com> wrote:
> >
> > i posted this bug to bugzilla with the attached patch.
> > this email is to notify the maintainers.
> > https://bugzilla.kernel.org/show_bug.cgi?id=206259
> >
> > thanks!
> >
> > js
> > ----
> >
> > ELAN i2c digitizer on microsoft surface go fails to initialize and
> > device is non-functional
> >
> > initialization fails on 4.19.96:
> > ----
> > [    5.507245] hid-generic 0018:04F3:261A.0005: report is too long
> > [    5.507256] hid-generic 0018:04F3:261A.0005: item 0 1 0 8 parsing failed
> > [    5.507290] hid-generic: probe of 0018:04F3:261A.0005 failed with error -22
> > [    5.556409] hid-multitouch 0018:04F3:261A.0005: report is too long
> > [    5.581641] hid-multitouch 0018:04F3:261A.0005: item 0 1 0 8 parsing failed
> > [    5.618495] hid-multitouch: probe of 0018:04F3:261A.0005 failed
> > with error -22
> >
> > initialization succeeds on 4.19.95:
> > ----
> > [    7.150887] hid-generic 0018:04F3:261A.0001: input,hidraw2: I2C HID
> > v1.00 Device [ELAN9038:00 04F3:261A] on i2c-ELAN9038:00
> > [    8.253077] input: ELAN9038:00 04F3:261A as
> > /devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-1/i2c-ELAN9038:00/0018:04F3:261A.0001/input/input20
> > [    8.253219] input: ELAN9038:00 04F3:261A Pen as
> > /devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-1/i2c-ELAN9038:00/0018:04F3:261A.0001/input/input23
> > [    8.253330] hid-multitouch 0018:04F3:261A.0001: input,hidraw0: I2C
> > HID v1.00 Device [ELAN9038:00 04F3:261A] on i2c-ELAN9038:00
> >
> > problem seems to be due to this commit:
> > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.19.y&id=31d06cc8e7caec36bedeb4f90444920431462f61
>