2015-02-20 17:45:35

by Seth Forshee

Subject: [PATCH] HID: i2c-hid: Limit reads to wMaxInputLength bytes for input events

d1c7e29e8d27 (HID: i2c-hid: prevent buffer overflow in early IRQ)
changed hid_get_input() to read ihid->bufsize bytes, which can be
more than wMaxInputLength. This is the case with the Dell XPS 13
9343, and it is causing events to be missed. In some cases the
missed events are releases, which can cause the cursor to jump or
freeze, among other problems. Limit the number of bytes read to
min(wMaxInputLength, ihid->bufsize) to prevent such problems.

Fixes: d1c7e29e8d27 "HID: i2c-hid: prevent buffer overflow in early IRQ"
Cc: Benjamin Tissoires <[email protected]>
Signed-off-by: Seth Forshee <[email protected]>
---
drivers/hid/i2c-hid/i2c-hid.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index d43e967..5e72fc2 100644
--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -370,7 +370,10 @@ static int i2c_hid_hwreset(struct i2c_client *client)
static void i2c_hid_get_input(struct i2c_hid *ihid)
{
int ret, ret_size;
- int size = ihid->bufsize;
+ int size = le16_to_cpu(ihid->hdesc.wMaxInputLength);
+
+ if (size > ihid->bufsize)
+ size = ihid->bufsize;

ret = i2c_master_recv(ihid->client, ihid->inbuf, size);
if (ret != size) {
--
1.9.1

2015-02-20 19:38:39

by Benjamin Tissoires

Subject: Re: [PATCH] HID: i2c-hid: Limit reads to wMaxInputLength bytes for input events

On Feb 20 2015 or thereabouts, Seth Forshee wrote:
> d1c7e29e8d27 (HID: i2c-hid: prevent buffer overflow in early IRQ)
> changed hid_get_input() to read ihid->bufsize bytes, which can be
> more than wMaxInputLength. This is the case with the Dell XPS 13
> 9343, and it is causing events to be missed. In some cases the
> missed events are releases, which can cause the cursor to jump or
> freeze, among other problems. Limit the number of bytes read to
> min(wMaxInputLength, ihid->bufsize) to prevent such problems.
>
> Fixes: d1c7e29e8d27 "HID: i2c-hid: prevent buffer overflow in early IRQ"
> Cc: Benjamin Tissoires <[email protected]>
> Signed-off-by: Seth Forshee <[email protected]>

Reviewed-by: Benjamin Tissoires <[email protected]>

Thanks!
Benjamin

> ---
> drivers/hid/i2c-hid/i2c-hid.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index d43e967..5e72fc2 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -370,7 +370,10 @@ static int i2c_hid_hwreset(struct i2c_client *client)
> static void i2c_hid_get_input(struct i2c_hid *ihid)
> {
> int ret, ret_size;
> - int size = ihid->bufsize;
> + int size = le16_to_cpu(ihid->hdesc.wMaxInputLength);
> +
> + if (size > ihid->bufsize)
> + size = ihid->bufsize;
>
> ret = i2c_master_recv(ihid->client, ihid->inbuf, size);
> if (ret != size) {
> --
> 1.9.1
>

2015-02-23 14:11:00

by Jiri Kosina

Subject: Re: [PATCH] HID: i2c-hid: Limit reads to wMaxInputLength bytes for input events

On Fri, 20 Feb 2015, Seth Forshee wrote:

> d1c7e29e8d27 (HID: i2c-hid: prevent buffer overflow in early IRQ)
> changed hid_get_input() to read ihid->bufsize bytes, which can be
> more than wMaxInputLength. This is the case with the Dell XPS 13
> 9343, and it is causing events to be missed. In some cases the
> missed events are releases, which can cause the cursor to jump or
> freeze, among other problems. Limit the number of bytes read to
> min(wMaxInputLength, ihid->bufsize) to prevent such problems.
>
> Fixes: d1c7e29e8d27 "HID: i2c-hid: prevent buffer overflow in early IRQ"
> Cc: Benjamin Tissoires <[email protected]>
> Signed-off-by: Seth Forshee <[email protected]>
> ---
> drivers/hid/i2c-hid/i2c-hid.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)

Applied, thanks.

> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index d43e967..5e72fc2 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -370,7 +370,10 @@ static int i2c_hid_hwreset(struct i2c_client *client)
> static void i2c_hid_get_input(struct i2c_hid *ihid)
> {
> int ret, ret_size;
> - int size = ihid->bufsize;
> + int size = le16_to_cpu(ihid->hdesc.wMaxInputLength);
> +
> + if (size > ihid->bufsize)
> + size = ihid->bufsize;
>
> ret = i2c_master_recv(ihid->client, ihid->inbuf, size);
> if (ret != size) {

--
Jiri Kosina
SUSE Labs