Commit 06edf928 authored by Seth Forshee's avatar Seth Forshee Committed by Luis Henriques

HID: i2c-hid: Limit reads to wMaxInputLength bytes for input events

commit 6d00f37e upstream.

d1c7e29e (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: d1c7e29e "HID: i2c-hid: prevent buffer overflow in early IRQ"
Signed-off-by: default avatarSeth Forshee <seth.forshee@canonical.com>
Reviewed-by: default avatarBenjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent 065f3735
...@@ -370,7 +370,10 @@ static int i2c_hid_hwreset(struct i2c_client *client) ...@@ -370,7 +370,10 @@ static int i2c_hid_hwreset(struct i2c_client *client)
static void i2c_hid_get_input(struct i2c_hid *ihid) static void i2c_hid_get_input(struct i2c_hid *ihid)
{ {
int ret, ret_size; 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); ret = i2c_master_recv(ihid->client, ihid->inbuf, size);
if (ret != size) { if (ret != size) {
......
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