From 4ce058df2ee02cc2a0f0fd5cd64ce6f1482a0b65 Mon Sep 17 00:00:00 2001 From: Zhang Cen Date: Tue, 19 May 2026 19:11:50 +0800 Subject: [PATCH] USB: serial: belkin_sa: validate interrupt status length The Belkin interrupt callback treats interrupt data as a four-byte status report and reads LSR/MSR fields at offsets 2 and 3. The interrupt-in buffer length is derived from endpoint wMaxPacketSize, and short interrupt transfers may complete successfully with a smaller actual_length. Check the completed interrupt packet length before parsing status fields so short interrupt endpoints and short successful packets are ignored instead of causing out-of-bounds or stale status-byte reads. KASAN report as below: BUG: KASAN: slab-out-of-bounds in belkin_sa_read_int_callback() Read of size 1 Call trace: belkin_sa_read_int_callback() (drivers/usb/serial/belkin_sa.c:202) __usb_hcd_giveback_urb() (drivers/usb/core/hcd.c:1630) dummy_timer() (?:?) Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Assisted-by: Codex:gpt-5.5 Signed-off-by: Zhang Cen Cc: stable@vger.kernel.org Signed-off-by: Johan Hovold --- drivers/usb/serial/belkin_sa.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/usb/serial/belkin_sa.c b/drivers/usb/serial/belkin_sa.c index 38ac910b1082..7bbd9523d4e9 100644 --- a/drivers/usb/serial/belkin_sa.c +++ b/drivers/usb/serial/belkin_sa.c @@ -194,6 +194,9 @@ static void belkin_sa_read_int_callback(struct urb *urb) usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data); + if (urb->actual_length < BELKIN_SA_MSR_INDEX + 1) + goto exit; + /* Handle known interrupt data */ /* ignore data[0] and data[1] */