CVE-2025-68362

In the Linux kernel, the following vulnerability has been resolved:

wifi: rtl818x: rtl8187: Fix potential buffer underflow in rtl8187_rx_cb()

The rtl8187_rx_cb() calculates the rx descriptor header address by subtracting its size from the skb tail pointer. However, it does not validate if the received packet (skb->len from urb->actual_length) is large enough to contain this header.

If a truncated packet is received, this will lead to a buffer underflow, reading memory before the start of the skb data area, and causing a kernel panic.

Add length checks for both rtl8187 and rtl8187b descriptor headers before attempting to access them, dropping the packet cleanly if the check fails.

The RTL8187 USB Wi-Fi RX path could read before the start of the skb buffer when handling truncated URBs, due to subtracting the RX header size from skb_tail_pointer() without validating skb->len. This can cause an out-of-bounds read and crash the kernel (DoS) without requiring authentication.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.