Vulnerabilidad en kernel de Linux (CVE-2022-49775)

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: tcp:cdg: permite llamar a tcp_cdg_release() varias veces. Aparentemente, mptcp puede llamar a tcp_disconnect() en un flujo ya desconectado. Esto generalmente funciona bien, a menos que el control de congestión actual sea CDG, ya que podría desencadenar una doble liberación [1]. En lugar de corregir MPTCP y futuros errores, podemos hacer que tcp_disconnect() sea más resistente. [1] ERROR: KASAN: doble liberación en slab_free mm/slub.c:3539 [en línea] ERROR: KASAN: doble liberación en kfree+0xe2/0x580 mm/slub.c:4567 CPU: 0 PID: 3645 Comm: kworker/0:7 No contaminado 6.0.0-syzkaller-02734-g0326074ff465 #0 Nombre del hardware: Google Google Compute Engine/Google Compute Engine, BIOS Google 22/09/2022 Cola de trabajo: eventos mptcp_worker Rastreo de llamadas: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:317 [inline] print_report.cold+0x2ba/0x719 mm/kasan/report.c:433 kasan_report_invalid_free+0x81/0x190 mm/kasan/report.c:462 ____kasan_slab_free+0x18b/0x1c0 mm/kasan/common.c:356 kasan_slab_free include/linux/kasan.h:200 [inline] slab_free_hook mm/slub.c:1759 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1785 slab_free mm/slub.c:3539 [inline] kfree+0xe2/0x580 mm/slub.c:4567 tcp_disconnect+0x980/0x1e20 net/ipv4/tcp.c:3145 __mptcp_close_ssk+0x5ca/0x7e0 net/mptcp/protocol.c:2327 mptcp_do_fastclose net/mptcp/protocol.c:2592 [inline] mptcp_worker+0x78c/0xff0 net/mptcp/protocol.c:2627 process_one_work+0x991/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e4/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 Allocated by task 3671: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:437 [inline] ____kasan_kmalloc mm/kasan/common.c:516 [inline] ____kasan_kmalloc mm/kasan/common.c:475 [inline] __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:525 kmalloc_array include/linux/slab.h:640 [inline] kcalloc include/linux/slab.h:671 [inline] tcp_cdg_init+0x10d/0x170 net/ipv4/tcp_cdg.c:380 tcp_init_congestion_control+0xab/0x550 net/ipv4/tcp_cong.c:193 tcp_reinit_congestion_control net/ipv4/tcp_cong.c:217 [inline] tcp_set_congestion_control+0x96c/0xaa0 net/ipv4/tcp_cong.c:391 do_tcp_setsockopt+0x505/0x2320 net/ipv4/tcp.c:3513 tcp_setsockopt+0xd4/0x100 net/ipv4/tcp.c:3801 mptcp_setsockopt+0x35f/0x2570 net/mptcp/sockopt.c:844 __sys_setsockopt+0x2d6/0x690 net/socket.c:2252 __do_sys_setsockopt net/socket.c:2263 [inline] __se_sys_setsockopt net/socket.c:2260 [inline] __x64_sys_setsockopt+0xba/0x150 net/socket.c:2260 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 16: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track+0x21/0x30 mm/kasan/common.c:45 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 ____kasan_slab_free mm/kasan/common.c:367 [inline] ____kasan_slab_free+0x166/0x1c0 mm/kasan/common.c:329 kasan_slab_free include/linux/kasan.h:200 [inline] slab_free_hook mm/slub.c:1759 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1785 slab_free mm/slub.c:3539 [inline] kfree+0xe2/0x580 mm/slub.c:4567 tcp_cleanup_congestion_control+0x70/0x120 net/ipv4/tcp_cong.c:226 tcp_v4_destroy_sock+0xdd/0x750 net/ipv4/tcp_ipv4.c:2254 tcp_v6_destroy_sock+0x11/0x20 net/ipv6/tcp_ipv6.c:1969 inet_csk_destroy_sock+0x196/0x440 net/ipv4/inet_connection_sock.c:1157 tcp_done+0x23b/0x340 net/ipv4/tcp.c:4649 tcp_rcv_state_process+0x40e7/0x4990 net/ipv4/tcp_input.c:6624 tcp_v6_do_rcv+0x3fc/0x13c0 net/ipv6/tcp_ipv6.c:1525 tcp_v6_rcv+0x2e8e/0x3830 net/ipv6/tcp_ipv6.c:1759 ip6_protocol_deliver_rcu+0x2db/0x1950 net/ipv6/ip6_input.c:439 ip6_input_finish+0x14c/0x2c0 net/ipv6/ip6_input.c:484 NF_HOOK include/linux/netfilter.h:302 [inline] NF_HOOK include/linux/netfilter.h:296 [inline] ip6_input+0x9c/0xd ---truncado---