On Fri, 21 Feb 2025 14:12:19 +0800 Jiayuan Chen wrote: > + /* Check if we should pass this packet. > + * BPF filter instructions assume each PPP packet has a 4-byte > + * header (e.g., those generated by libpcap), and then default > + * to skipping the first 2 bytes at the beginning of the > + * instruction. However, we still need to initialize these > + * 2-byte new headers to prevent crafted BPF programs from > + * reading them which would cause reading of uninitialized > + * data. Here, we set the headers according to the RFC 1662. > + */ > + *(u16 *)skb_push(skb, 2) = htons(0xff03); The constant from the RFC deserves a #define or enum. Looks like we may already need it in one other place: drivers/net/wan/fsl_ucc_hdlc.h:#define DEFAULT_PPP_HEAD 0xff03 -- pw-bot: cr
