CyberRota Analysis
AI-GeneratedThe vulnerability affects the Linux kernel's IP-in-IP (ipip) and MPLS-in-IP (mplsip) tunnel handlers, where a failure to allocate metadata during packet processing leads to a memory leak of socket buffers (skbs). This issue can result in increased memory consumption over time, potentially degrading system performance or leading to denial-of-service conditions. Administrators managing Linux systems utilizing ipip or mplsip tunnels in collect_md mode should prioritize addressing this vulnerability to prevent resource exhaustion.
Original NVD Description
In the Linux kernel, the following vulnerability has been resolved: ipip: fix skb leak in collect_md mode when metadata_dst allocation fails In collect_md mode ipip_tunnel_rcv() returns 0 without freeing the skb when ip_tun_rx_dst() fails to allocate the metadata_dst. ipip_rcv() and mplsip_rcv() are registered as xfrm_tunnel handlers, so tunnel4_rcv() and tunnelmpls4_rcv() read the zero return as "the packet has been consumed" and do not free it either. The skb is leaked. The other tunnel drivers all dispose of the packet at this point: ip6_tunnel.c jumps to its drop label, ip_gre.c and ip6_gre.c return PACKET_REJECT, which makes gre_rcv() free the skb. Only ipip returns 0. Jump to the existing drop label instead. It frees the skb and still returns 0, so the packet keeps being reported as consumed, which is what we want here: the outer header has already been pulled, and neither the remaining handlers nor an ICMP unreachable have any use for it. Triggering this needs an ipip or mplsip tunnel in collect_md mode and an atomic allocation failure, which is why it has gone unnoticed.