CVE-2024-36938

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: bpf, skmsg: Se corrigió la desreferencia del puntero NULL en sk_psock_skb_ingress_enqueue Se corrigieron las ejecucións de datos del puntero NULL en sk_psock_skb_ingress_enqueue() que syzbot informó [1]. [1] ERROR: KCSAN: ejecución de datos en sk_psock_drop / sk_psock_skb_ingress_enqueue escribe en 0xffff88814b3278b8 de 8 bytes por tarea 10724 en la CPU 1: sk_psock_stop_verdict net/core/skmsg.c:1257 [en línea] 0 neto/núcleo/skmsg .c:843 sk_psock_put include/linux/skmsg.h:459 [en línea] sock_map_close+0x1a7/0x260 net/core/sock_map.c:1648 unix_release+0x4b/0x80 net/unix/af_unix.c:1048 __sock_release net/socket. c:659 [en línea] sock_close+0x68/0x150 net/socket.c:1421 __fput+0x2c1/0x660 fs/file_table.c:422 __fput_sync+0x44/0x60 fs/file_table.c:507 __do_sys_close fs/open.c:1556 [en línea] __se_sys_close+0x101/0x1b0 fs/open.c:1541 __x64_sys_close+0x1f/0x30 fs/open.c:1541 do_syscall_64+0xd3/0x1d0 Entry_SYSCALL_64_after_hwframe+0x6d/0x75 leer en 0xffff8881 4b3278b8 de 8 bytes por tarea 10713 en la CPU 0: sk_psock_data_ready include/linux/skmsg.h:464 [en línea] sk_psock_skb_ingress_enqueue+0x32d/0x390 net/core/skmsg.c:555 sk_psock_skb_ingress_self+0x185/0x1e0 net/core/skmsg.c:606 sk_psock_verdict_apply net /core/skmsg.c: 1008 [en línea] sk_psock_verdict_recv+0x3e4/0x4a0 net/core/skmsg.c:1202 unix_read_skb net/unix/af_unix.c:2546 [en línea] unix_stream_read_skb+0x9e/0xf0 net/unix/af_unix.c:2682 +0x77/0x220 net/core/skmsg.c:1223 unix_stream_sendmsg+0x527/0x860 net/unix/af_unix.c:2339 sock_sendmsg_nosec net/socket.c:730 [en línea] __sock_sendmsg+0x140/0x180 net/socket.c:745 ____sys_sendmsg+0x 312/ 0x410 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [en línea] __sys_sendmsg+0x1e9/0x280 net/socket.c:2667 __do_sys_sendmsg net/socket.c:2676 [en línea] __se_sys_sendmsg net/socket. c:2674 [en línea] __x64_sys_sendmsg+0x46/0x50 net/socket.c:2674 do_syscall_64+0xd3/0x1d0 Entry_SYSCALL_64_after_hwframe+0x6d/0x75 valor cambiado: 0xffffffff83d7feb0 -> 0x0000000000000000 editado por Kernel Concurrency Sanitizer en: CPU: 0 PID: 10713 Comm: syz-executor .4 Contaminado: GW 6.8.0-syzkaller-08951-gfe46a7dd189e #0 Nombre del hardware: Google Google Compute Engine/Google Compute Engine, BIOS Google 29/02/2024 Antes de esto, confirme 4cd12c6065df ("bpf, sockmap: corrija el puntero NULL dereference in sk_psock_verdict_data_ready()") arregló un puntero NULL de manera similar debido a que no hay protección de save_data_ready. Aquí hay otra persona que llama y causa el mismo problema por el mismo motivo. Entonces deberíamos protegerlo con el bloqueo de lectura sk_callback_lock porque el lado del escritor en sk_psock_drop() usa "write_lock_bh(&sk->sk_callback_lock);". Para evitar errores que podrían ocurrir en el futuro, muevo esos dos pares de candados a sk_psock_data_ready(), sugerido por John Fastabend.

In the Linux kernel, the following vulnerability has been resolved: bpf, skmsg: Fix NULL pointer dereference in sk_psock_skb_ingress_enqueue Fix NULL pointer data-races in sk_psock_skb_ingress_enqueue() which syzbot reported [1]. [1] BUG: KCSAN: data-race in sk_psock_drop / sk_psock_skb_ingress_enqueue write to 0xffff88814b3278b8 of 8 bytes by task 10724 on cpu 1: sk_psock_stop_verdict net/core/skmsg.c:1257 [inline] sk_psock_drop+0x13e/0x1f0 net/core/skmsg.c:843 sk_psock_put include/linux/skmsg.h:459 [inline] sock_map_close+0x1a7/0x260 net/core/sock_map.c:1648 unix_release+0x4b/0x80 net/unix/af_unix.c:1048 __sock_release net/socket.c:659 [inline] sock_close+0x68/0x150 net/socket.c:1421 __fput+0x2c1/0x660 fs/file_table.c:422 __fput_sync+0x44/0x60 fs/file_table.c:507 __do_sys_close fs/open.c:1556 [inline] __se_sys_close+0x101/0x1b0 fs/open.c:1541 __x64_sys_close+0x1f/0x30 fs/open.c:1541 do_syscall_64+0xd3/0x1d0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 read to 0xffff88814b3278b8 of 8 bytes by task 10713 on cpu 0: sk_psock_data_ready include/linux/skmsg.h:464 [inline] sk_psock_skb_ingress_enqueue+0x32d/0x390 net/core/skmsg.c:555 sk_psock_skb_ingress_self+0x185/0x1e0 net/core/skmsg.c:606 sk_psock_verdict_apply net/core/skmsg.c:1008 [inline] sk_psock_verdict_recv+0x3e4/0x4a0 net/core/skmsg.c:1202 unix_read_skb net/unix/af_unix.c:2546 [inline] unix_stream_read_skb+0x9e/0xf0 net/unix/af_unix.c:2682 sk_psock_verdict_data_ready+0x77/0x220 net/core/skmsg.c:1223 unix_stream_sendmsg+0x527/0x860 net/unix/af_unix.c:2339 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x140/0x180 net/socket.c:745 ____sys_sendmsg+0x312/0x410 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x1e9/0x280 net/socket.c:2667 __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x46/0x50 net/socket.c:2674 do_syscall_64+0xd3/0x1d0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 value changed: 0xffffffff83d7feb0 -> 0x0000000000000000 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 10713 Comm: syz-executor.4 Tainted: G W 6.8.0-syzkaller-08951-gfe46a7dd189e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 Prior to this, commit 4cd12c6065df ("bpf, sockmap: Fix NULL pointer dereference in sk_psock_verdict_data_ready()") fixed one NULL pointer similarly due to no protection of saved_data_ready. Here is another different caller causing the same issue because of the same reason. So we should protect it with sk_callback_lock read lock because the writer side in the sk_psock_drop() uses "write_lock_bh(&sk->sk_callback_lock);". To avoid errors that could happen in future, I move those two pairs of lock into the sk_psock_data_ready(), which is suggested by John Fastabend.

Benedict Schlüter, Supraja Sridhara, Andrin Bertschi, and Shweta Shinde discovered that an untrusted hypervisor could inject malicious #VC interrupts and compromise the security guarantees of AMD SEV-SNP. This flaw is known as WeSee. A local attacker in control of the hypervisor could use this to expose sensitive information or possibly execute arbitrary code in the trusted execution environment. Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system.