CVE-2021-47591

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: mptcp: elimina el soporte de tcp ulp setsockopt TCP_ULP setsockopt no se puede usar para mptcp porque ya se usa internamente para conectar sockets de subflujo (tcp) a la capa mptcp. syzbot logró desencadenar un bloqueo para las conexiones mptcp que están en modo alternativo: KASAN: null-ptr-deref en el rango [0x0000000000000020-0x0000000000000027] CPU: 1 PID: 1083 Comm: syz-executor.3 Not tainted 5.16.0-rc2- syzkaller #0 RIP: 0010:tls_build_proto net/tls/tls_main.c:776 [en línea] [..] __tcp_set_ulp net/ipv4/tcp_ulp.c:139 [en línea] tcp_set_ulp+0x428/0x4c0 net/ipv4/tcp_ulp.c: 160 do_tcp_setsockopt+0x455/0x37c0 net/ipv4/tcp.c:3391 mptcp_setsockopt+0x1b47/0x2400 net/mptcp/sockopt.c:638 Elimina la compatibilidad con TCP_ULP setsockopt.

In the Linux kernel, the following vulnerability has been resolved: mptcp: remove tcp ulp setsockopt support TCP_ULP setsockopt cannot be used for mptcp because its already used internally to plumb subflow (tcp) sockets to the mptcp layer. syzbot managed to trigger a crash for mptcp connections that are in fallback mode: KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027] CPU: 1 PID: 1083 Comm: syz-executor.3 Not tainted 5.16.0-rc2-syzkaller #0 RIP: 0010:tls_build_proto net/tls/tls_main.c:776 [inline] [..] __tcp_set_ulp net/ipv4/tcp_ulp.c:139 [inline] tcp_set_ulp+0x428/0x4c0 net/ipv4/tcp_ulp.c:160 do_tcp_setsockopt+0x455/0x37c0 net/ipv4/tcp.c:3391 mptcp_setsockopt+0x1b47/0x2400 net/mptcp/sockopt.c:638 Remove support for TCP_ULP setsockopt.