// For flags

CVE-2024-36938

bpf, skmsg: Fix NULL pointer dereference in sk_psock_skb_ingress_enqueue

Severity Score

5.5
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

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.

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.

*Credits: N/A
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-05-30 CVE Reserved
  • 2024-05-30 CVE Published
  • 2024-06-11 EPSS Updated
  • 2024-12-19 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-476: NULL Pointer Dereference
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 4.20 < 5.10.223
Search vendor "Linux" for product "Linux Kernel" and version " >= 4.20 < 5.10.223"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 4.20 < 5.15.159
Search vendor "Linux" for product "Linux Kernel" and version " >= 4.20 < 5.15.159"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 4.20 < 6.1.91
Search vendor "Linux" for product "Linux Kernel" and version " >= 4.20 < 6.1.91"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 4.20 < 6.6.31
Search vendor "Linux" for product "Linux Kernel" and version " >= 4.20 < 6.6.31"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 4.20 < 6.8.10
Search vendor "Linux" for product "Linux Kernel" and version " >= 4.20 < 6.8.10"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 4.20 < 6.9
Search vendor "Linux" for product "Linux Kernel" and version " >= 4.20 < 6.9"
en
Affected