From: Seungjin Bae <eeodqql09@gmail.com>
The `ttusb_dec_process_urb_frame()` parses the PVA packet from the
USB device. However, it doesn't check whether the calculated
`packet_payload_length` exceeds the size of the `packet` buffer.
The `packet` buffer has a fixed size of `MAX_PVA_LENGTH + 4`. However,
`packet_payload_length` is derived from 2 bytes of the input data,
allowing a maximum value of 65543 bytes (8 + 0xFFFF).
If a malicious USB device sends a packet with crafted data, it
triggers a heap buffer overflow. This allows an attacker to overwrite
adjacent fields in the `struct ttusb_dec`. Specifically, the `a_pes2ts`
field, which contains a callback function pointer, is located after the
`packet` buffer. Overwriting this pointer can lead to control flow
hijacking.
Fix this by adding a bounds check for the parsed length against the
buffer size.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Co-developed-by: Sanghoon Choi <csh0052@gmail.com>
Signed-off-by: Sanghoon Choi <csh0052@gmail.com>
Signed-off-by: Seungjin Bae <eeodqql09@gmail.com>
---
v1 -> v2: Change warning function
v2 -> v3: Add missing comma in the dev_warn argument
v3 -> v4: Edit alignment
drivers/media/usb/ttusb-dec/ttusb_dec.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/media/usb/ttusb-dec/ttusb_dec.c b/drivers/media/usb/ttusb-dec/ttusb_dec.c
index b4575fe89c95..17c7a8d5ada9 100644
--- a/drivers/media/usb/ttusb-dec/ttusb_dec.c
+++ b/drivers/media/usb/ttusb-dec/ttusb_dec.c
@@ -703,10 +703,19 @@ static void ttusb_dec_process_urb_frame(struct ttusb_dec *dec, u8 *b,
if (dec->packet_type == TTUSB_DEC_PACKET_PVA &&
dec->packet_length == 8) {
- dec->packet_state++;
- dec->packet_payload_length = 8 +
+ int len = 8 +
(dec->packet[6] << 8) +
dec->packet[7];
+
+ if (len > MAX_PVA_LENGTH + 4) {
+ dev_warn(&dec->udev->dev,
+ "%s: packet too long - discarding\n",
+ __func__);
+ dec->packet_state = 0;
+ } else {
+ dec->packet_state++;
+ dec->packet_payload_length = len;
+ }
} else if (dec->packet_type ==
TTUSB_DEC_PACKET_SECTION &&
dec->packet_length == 5) {
--
2.43.0