diff options
| author | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-04-20 18:00:27 +0200 |
|---|---|---|
| committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2026-04-26 21:00:25 -0700 |
| commit | 2905281cbda52ec9df540113b35b835feb5fafd3 (patch) | |
| tree | 16d64b82e4d450b29ad42731939218f84b294a16 /drivers/input | |
| parent | 8f9d6cd6d3916add4c47a9dd1622e4fc057f877b (diff) | |
Input: usbtouchscreen - clamp NEXIO data_len/x_len to URB buffer size
nexio_read_data() pulls data_len and x_len from a packed __be16 header
in the device's interrupt packet and then walks packet->data[0..x_len)
and packet->data[x_len..data_len) comparing each byte against a
threshold.
Both fields are 16-bit on the wire (max 65535). The existing
adjustments shave at most 0x100 / 0x80 off, so the loop bound can still
reach roughly 0xfeff. The URB transfer buffer for NEXIO is rept_size
(1024) bytes from usb_alloc_coherent(), with the first 7 occupied by the
packed header — so packet->data[] has 1017 valid bytes. read_data()
callbacks are not given urb->actual_length, and nothing else bounds the
walk.
A device that lies about its length can get a ~64 KiB out-of-bounds read
past the coherent DMA allocation. The first index whose byte exceeds
NEXIO_THRESHOLD lands in begin_x / begin_y and from there into the
reported touch coordinates, so adjacent kernel memory contents leak to
userspace as ABS_X / ABS_Y events. Far enough out, the read can also
hit an unmapped page and fault.
Fix this all by clamping data_len to the buffer's data[] capacity and
x_len to data_len.
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Fixes: 5197424cdccc ("Input: usbtouchscreen - add NEXIO (or iNexio) support")
Cc: stable <stable@kernel.org>
Assisted-by: gkh_clanker_t1000
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/2026042026-chlorine-epidermis-fd6d@gregkh
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'drivers/input')
| -rw-r--r-- | drivers/input/touchscreen/usbtouchscreen.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c index daa28135f887..0bbacb517c28 100644 --- a/drivers/input/touchscreen/usbtouchscreen.c +++ b/drivers/input/touchscreen/usbtouchscreen.c @@ -1067,6 +1067,11 @@ static int nexio_read_data(struct usbtouch_usb *usbtouch, unsigned char *pkt) if (x_len > 0xff) x_len -= 0x80; + if (data_len > usbtouch->data_size - sizeof(*packet)) + data_len = usbtouch->data_size - sizeof(*packet); + if (x_len > data_len) + x_len = data_len; + /* send ACK */ ret = usb_submit_urb(priv->ack, GFP_ATOMIC); if (ret) |