CVE-2024-36904

En el kernel de Linux se ha resuelto la siguiente vulnerabilidad: tcp: utilice refcount_inc_not_zero() en tcp_twsk_unique(). Anderson Nascimento informó sobre un símbolo de use after free en tcp_twsk_unique() con un buen análisis. Desde el commit ec94c2696f0b ("tcp/dccp: evitar una operación atómica para timewait hashdance"), inet_twsk_hashdance() establece el sk_refcnt del socket TIME-WAIT después de ponerlo en ehash y liberar el bloqueo del depósito. Por lo tanto, hay una pequeña ventana de ejecución donde otros subprocesos podrían intentar reutilizar el puerto durante connect() y llamar a sock_hold() en tcp_twsk_unique() para el socket TIME-WAIT con cero refcnt. Si eso sucede, el refcnt tomado por tcp_twsk_unique() se sobrescribe y sock_put() provocará un desbordamiento insuficiente, lo que desencadenará un use after free real en otro lugar. Para evitar el use after free, debemos usar refcount_inc_not_zero() en tcp_twsk_unique() y renunciar a reutilizar el puerto si devuelve falso. [0]: refcount_t: suma en 0; use after free. ADVERTENCIA: CPU: 0 PID: 1039313 en lib/refcount.c:25 refcount_warn_saturate+0xe5/0x110 CPU: 0 PID: 1039313 Comm: disparador No contaminado 6.8.6-200.fc39.x86_64 #1 Nombre de hardware: VMware, Inc. Plataforma de referencia de escritorio VMware20,1/440BX, BIOS VMW201.00V.21805430.B64.2305221830 22/05/2023 RIP: 0010:refcount_warn_saturate+0xe5/0x110 Código: 42 8e ff 0f 0b c3 cc cc cc 80 3d aa 13 cada uno 01 00 0f 85 5e ff ff 48 c7 c7 f8 8e b7 82 c6 05 96 13 ea 01 01 e8 7b 42 8e ff <0f> 0b c3 cc cc cc cc 48 c7 c7 50 8f b7 82 c6 05 7a 13 ea 0 1 e8 RSP: 0018:ffffc90006b43b60 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff888009bb3ef0 RCX: 00000000000000027 RDX: ffff88807be218c8 RSI: 00000000001 RDI: ffff88807be218c0 RBP: 0000000000069d70 R08: 0000000000000000 R09: ffffc90006b439f0 R10: ffffc90006b439e8 R11: 000000000000 0003 R12: ffff8880029ede84 R13: 0000000000004e20 R14: ffffffff84356dc0 R15: ffff888009bb3ef0 FS: 00007f62c10926c0(0000) GS:ffff88807be00000(0000) knlGS:00000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020ccb000 CR3: 000000004628c005 CR4: 0000000000f70ef0 PKRU: 55555554 Seguimiento de llamadas: ? refcount_warn_saturate+0xe5/0x110? __advertir+0x81/0x130 ? refcount_warn_saturate+0xe5/0x110? report_bug+0x171/0x1a0? refcount_warn_saturate+0xe5/0x110? handle_bug+0x3c/0x80? exc_invalid_op+0x17/0x70? asm_exc_invalid_op+0x1a/0x20? refcount_warn_saturate+0xe5/0x110 tcp_twsk_unique+0x186/0x190 __inet_check_establecido+0x176/0x2d0 __inet_hash_connect+0x74/0x7d0 ? __pfx___inet_check_establecido+0x10/0x10 tcp_v4_connect+0x278/0x530 __inet_stream_connect+0x10f/0x3d0 inet_stream_connect+0x3a/0x60 __sys_connect+0xa8/0xd0 __x64_sys_connect+0x18/0x20 _64+0x83/0x170 entrada_SYSCALL_64_after_hwframe+0x78/0x80 RIP: 0033:0x7f62c11a885d Código: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff 73 01 c3 48 8b 0d a3 45 0c 00 f7 d8 64 89 01 48 RSP: 002b:00007f62c1091e58 EFLAGS: 00000296 ORIG_RAX: 0000000000000002a RAX: ffffffffffffffda RBX: 20ccb004 RCX: 00007f62c11a885d RDX: 00000000000000010 RSI: 0000000020ccb000 RDI: 0000000000000003 RBP: 00007f62c1091e90 R08: 0000000000000 0000R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 00007f62c10926c0 R13: ffffffffffffff88 R14: 0000000000000000 R15: 07ffe237885b0

A use-after-free flaw was found in the Linux kernel’s TCP protocol in how a local user triggers a complex race condition during connection to the socket. This flaw allows a local user to crash or potentially escalate their privileges on the system.

In the Linux kernel, the following vulnerability has been resolved: tcp: Use refcount_inc_not_zero() in tcp_twsk_unique(). Anderson Nascimento reported a use-after-free splat in tcp_twsk_unique() with nice analysis. Since commit ec94c2696f0b ("tcp/dccp: avoid one atomic operation for timewait hashdance"), inet_twsk_hashdance() sets TIME-WAIT socket's sk_refcnt after putting it into ehash and releasing the bucket lock. Thus, there is a small race window where other threads could try to reuse the port during connect() and call sock_hold() in tcp_twsk_unique() for the TIME-WAIT socket with zero refcnt. If that happens, the refcnt taken by tcp_twsk_unique() is overwritten and sock_put() will cause underflow, triggering a real use-after-free somewhere else. To avoid the use-after-free, we need to use refcount_inc_not_zero() in tcp_twsk_unique() and give up on reusing the port if it returns false. [0]: refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 1039313 at lib/refcount.c:25 refcount_warn_saturate+0xe5/0x110 CPU: 0 PID: 1039313 Comm: trigger Not tainted 6.8.6-200.fc39.x86_64 #1 Hardware name: VMware, Inc. VMware20,1/440BX Desktop Reference Platform, BIOS VMW201.00V.21805430.B64.2305221830 05/22/2023 RIP: 0010:refcount_warn_saturate+0xe5/0x110 Code: 42 8e ff 0f 0b c3 cc cc cc cc 80 3d aa 13 ea 01 00 0f 85 5e ff ff ff 48 c7 c7 f8 8e b7 82 c6 05 96 13 ea 01 01 e8 7b 42 8e ff <0f> 0b c3 cc cc cc cc 48 c7 c7 50 8f b7 82 c6 05 7a 13 ea 01 01 e8 RSP: 0018:ffffc90006b43b60 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff888009bb3ef0 RCX: 0000000000000027 RDX: ffff88807be218c8 RSI: 0000000000000001 RDI: ffff88807be218c0 RBP: 0000000000069d70 R08: 0000000000000000 R09: ffffc90006b439f0 R10: ffffc90006b439e8 R11: 0000000000000003 R12: ffff8880029ede84 R13: 0000000000004e20 R14: ffffffff84356dc0 R15: ffff888009bb3ef0 FS: 00007f62c10926c0(0000) GS:ffff88807be00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020ccb000 CR3: 000000004628c005 CR4: 0000000000f70ef0 PKRU: 55555554 Call Trace: <TASK> ? refcount_warn_saturate+0xe5/0x110 ? __warn+0x81/0x130 ? refcount_warn_saturate+0xe5/0x110 ? report_bug+0x171/0x1a0 ? refcount_warn_saturate+0xe5/0x110 ? handle_bug+0x3c/0x80 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? refcount_warn_saturate+0xe5/0x110 tcp_twsk_unique+0x186/0x190 __inet_check_established+0x176/0x2d0 __inet_hash_connect+0x74/0x7d0 ? __pfx___inet_check_established+0x10/0x10 tcp_v4_connect+0x278/0x530 __inet_stream_connect+0x10f/0x3d0 inet_stream_connect+0x3a/0x60 __sys_connect+0xa8/0xd0 __x64_sys_connect+0x18/0x20 do_syscall_64+0x83/0x170 entry_SYSCALL_64_after_hwframe+0x78/0x80 RIP: 0033:0x7f62c11a885d Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d a3 45 0c 00 f7 d8 64 89 01 48 RSP: 002b:00007f62c1091e58 EFLAGS: 00000296 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 0000000020ccb004 RCX: 00007f62c11a885d RDX: 0000000000000010 RSI: 0000000020ccb000 RDI: 0000000000000003 RBP: 00007f62c1091e90 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 00007f62c10926c0 R13: ffffffffffffff88 R14: 0000000000000000 R15: 00007ffe237885b0 </TASK>

This update for the Linux Kernel 5.14.21-150400_24_119 fixes several issues. The following security issues were fixed. Vsock/virtio: Initialization of the dangling pointer occurring in vsk->trans. Ipv6: avoid use-after-free in ip6_fragment. Tcp: Use refcount_inc_not_zero in tcp_twsk_unique. Fixed memory leak for not ip packets. Fixed int overflow for stack access size. Sch_cake: do not call cake_destroy from cake_init. Fixed potential UAF in is_valid_oplock_break. Smb: client: fix use-after-free bug in cifs_debug_data_proc_show. Fixed potential UAF in smb2_is_network_name_deleted. Fixed potential UAF in cifs_stats_proc_show. Fixed potential UAF in smb2_is_valid_lease_break. Fixed potential UAF in cifs_signal_cifsd_for_reconnect. Gpiolib: cdev: Fix use after free in lineinfo_changed_notify. Gpiolib: cdev: Fix use after free in lineinfo_changed_notify. Net: do not leave a dangling sk pointer, when socket creation fails hfsplus: fix uninit-value in copy_name. Fs/9p: only translate RWX permissions for plain 9P2000. Hsr: Prevent use after free in prp_create_tagged_frame. Set gtt bound flag in amdgpu_ttm_gart_bind. Fixed use-after-free bugs caused by sco_sock_timeout. Drm/client: Fully protect modes with dev->mode_config.mutex. Fixed false-positive lockdep splat for spin_lock in __unix_gc. Fixed double free of the ha->vp_map pointer. Fixed underflow in parse_server_interfaces. Fixed use-after-free in ip6_route_mpath_notify.