CVE-2021-47451

netfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value

Severity Score

"-"

*CVSS v-

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Track

*SSVC

Descriptions

In the Linux kernel, the following vulnerability has been resolved:

netfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value

Currently, when the rule related to IDLETIMER is added, idletimer_tg timer
structure is initialized by kmalloc on executing idletimer_tg_create
function. However, in this process timer->timer_type is not defined to
a specific value. Thus, timer->timer_type has garbage value and it occurs
kernel panic. So, this commit fixes the panic by initializing
timer->timer_type using kzalloc instead of kmalloc.

Test commands:
# iptables -A OUTPUT -j IDLETIMER --timeout 1 --label test
$ cat /sys/class/xt_idletimer/timers/test
Killed

Splat looks like:
BUG: KASAN: user-memory-access in alarm_expires_remaining+0x49/0x70
Read of size 8 at addr 0000002e8c7bc4c8 by task cat/917
CPU: 12 PID: 917 Comm: cat Not tainted 5.14.0+ #3 79940a339f71eb14fc81aee1757a20d5bf13eb0e
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
dump_stack_lvl+0x6e/0x9c
kasan_report.cold+0x112/0x117
? alarm_expires_remaining+0x49/0x70
__asan_load8+0x86/0xb0
alarm_expires_remaining+0x49/0x70
idletimer_tg_show+0xe5/0x19b [xt_IDLETIMER 11219304af9316a21bee5ba9d58f76a6b9bccc6d]
dev_attr_show+0x3c/0x60
sysfs_kf_seq_show+0x11d/0x1f0
? device_remove_bin_file+0x20/0x20
kernfs_seq_show+0xa4/0xb0
seq_read_iter+0x29c/0x750
kernfs_fop_read_iter+0x25a/0x2c0
? __fsnotify_parent+0x3d1/0x570
? iov_iter_init+0x70/0x90
new_sync_read+0x2a7/0x3d0
? __x64_sys_llseek+0x230/0x230
? rw_verify_area+0x81/0x150
vfs_read+0x17b/0x240
ksys_read+0xd9/0x180
? vfs_write+0x460/0x460
? do_syscall_64+0x16/0xc0
? lockdep_hardirqs_on+0x79/0x120
__x64_sys_read+0x43/0x50
do_syscall_64+0x3b/0xc0
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f0cdc819142
Code: c0 e9 c2 fe ff ff 50 48 8d 3d 3a ca 0a 00 e8 f5 19 02 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24
RSP: 002b:00007fff28eee5b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f0cdc819142
RDX: 0000000000020000 RSI: 00007f0cdc032000 RDI: 0000000000000003
RBP: 00007f0cdc032000 R08: 00007f0cdc031010 R09: 0000000000000000
R10: 0000000000000022 R11: 0000000000000246 R12: 00005607e9ee31f0
R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: netfilter: xt_IDLETIMER: corrige el pánico que ocurre cuando timer_type tiene valor basura Actualmente, cuando se agrega la regla relacionada con IDLETIMER, kmalloc inicializa la estructura del temporizador idletimer_tg al ejecutar la función idletimer_tg_create. Sin embargo, en este proceso timer->timer_type no está definido en un valor específico. Por lo tanto, timer->timer_type tiene un valor basura y se produce un pánico en el kernel. Entonces, esta confirmación soluciona el pánico al inicializar timer->timer_type usando kzalloc en lugar de kmalloc. Comandos de prueba: # iptables -A OUTPUT -j IDLETIMER --timeout 1 --label test $ cat /sys/class/xt_idletimer/timers/test Killed Splat se ve así: ERROR: KASAN: acceso a memoria de usuario en alarm_expires_remaining+0x49/ 0x70 Lectura del tamaño 8 en la dirección 0000002e8c7bc4c8 por tarea cat/917 CPU: 12 PID: 917 Comm: cat Not tainted 5.14.0+ #3 79940a339f71eb14fc81aee1757a20d5bf13eb0e Nombre del hardware: PC estándar QEMU (Q35 + ICH9, 009), BIOS 1.13.0- 1ubuntu1.1 01/04/2014 Seguimiento de llamadas: dump_stack_lvl+0x6e/0x9c kasan_report.cold+0x112/0x117 ? alarm_expires_remaining+0x49/0x70 __asan_load8+0x86/0xb0 alarm_expires_remaining+0x49/0x70 idletimer_tg_show+0xe5/0x19b [xt_IDLETIMER 11219304af9316a21bee5ba9d58f76a6b9bccc6d] tr_show+0x3c/0x60 sysfs_kf_seq_show+0x11d/0x1f0 ? device_remove_bin_file+0x20/0x20 kernfs_seq_show+0xa4/0xb0 seq_read_iter+0x29c/0x750 kernfs_fop_read_iter+0x25a/0x2c0 ? __fsnotify_parent+0x3d1/0x570? iov_iter_init+0x70/0x90 new_sync_read+0x2a7/0x3d0? __x64_sys_llseek+0x230/0x230 ? rw_verify_area+0x81/0x150 vfs_read+0x17b/0x240 ksys_read+0xd9/0x180 ? vfs_write+0x460/0x460? do_syscall_64+0x16/0xc0? lockdep_hardirqs_on+0x79/0x120 __x64_sys_read+0x43/0x50 do_syscall_64+0x3b/0xc0 Entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f0cdc819142 Código: c0 e9 c2 fe ff ff 50 48 8d 3d 3a ca 0a 00 e8 f5 19 02 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24 RSP: :00007fff28eee5b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 000000000020000 RCX: 00007f0cdc819142 RDX: 0000000000020000 RSI: 00007f0cdc03200 0 RDI: 0000000000000003 RBP: 00007f0cdc032000 R08: 00007f0cdc031010 R09: 0000000000000000 R10: 0000000000000022 R11: 00000000000000246 R 12: 00005607e9ee31f0 R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000

*Credits: N/A

CVSS Scores

Attack Vector

Attack Complexity

Privileges Required

User Interaction

Scope

Confidentiality

Integrity

Availability

* Common Vulnerability Scoring System

SSVC

Decision:Track

Exploitation

None

Automatable

Tech. Impact

Partial

* Organization's Worst-case Scenario

Timeline

2024-05-21 CVE Reserved
2024-05-22 CVE Published
2024-05-22 EPSS Updated
2024-11-04 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CAPEC

References (4)

URL	Tag	Source
https://git.kernel.org/stable/c/68983a354a655c35d3fb204489d383a2a051fda7	Vuln. Introduced

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/2a670c323055282c9b72794a491d53cef86bbeaf	2021-10-27
https://git.kernel.org/stable/c/cae7cab804c943d723d52724a3aeb07a3f4a2650	2021-10-27
https://git.kernel.org/stable/c/902c0b1887522a099aa4e1e6b4b476c2fe5dd13e	2021-10-07

URL	Date	SRC

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"				>= 5.7 < 5.10.76 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.7 < 5.10.76"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.7 < 5.14.15 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.7 < 5.14.15"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.7 < 5.15 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.7 < 5.15"		en		Affected