CVE-2021-47274

tracing: Correct the length check which causes memory corruption

Severity Score

9.8

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Attend

*SSVC

Descriptions

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

tracing: Correct the length check which causes memory corruption

We've suffered from severe kernel crashes due to memory corruption on
our production environment, like,

Call Trace:
[1640542.554277] general protection fault: 0000 [#1] SMP PTI
[1640542.554856] CPU: 17 PID: 26996 Comm: python Kdump: loaded Tainted:G
[1640542.556629] RIP: 0010:kmem_cache_alloc+0x90/0x190
[1640542.559074] RSP: 0018:ffffb16faa597df8 EFLAGS: 00010286
[1640542.559587] RAX: 0000000000000000 RBX: 0000000000400200 RCX:
0000000006e931bf
[1640542.560323] RDX: 0000000006e931be RSI: 0000000000400200 RDI:
ffff9a45ff004300
[1640542.560996] RBP: 0000000000400200 R08: 0000000000023420 R09:
0000000000000000
[1640542.561670] R10: 0000000000000000 R11: 0000000000000000 R12:
ffffffff9a20608d
[1640542.562366] R13: ffff9a45ff004300 R14: ffff9a45ff004300 R15:
696c662f65636976
[1640542.563128] FS: 00007f45d7c6f740(0000) GS:ffff9a45ff840000(0000)
knlGS:0000000000000000
[1640542.563937] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1640542.564557] CR2: 00007f45d71311a0 CR3: 000000189d63e004 CR4:
00000000003606e0
[1640542.565279] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[1640542.566069] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400
[1640542.566742] Call Trace:
[1640542.567009] anon_vma_clone+0x5d/0x170
[1640542.567417] __split_vma+0x91/0x1a0
[1640542.567777] do_munmap+0x2c6/0x320
[1640542.568128] vm_munmap+0x54/0x70
[1640542.569990] __x64_sys_munmap+0x22/0x30
[1640542.572005] do_syscall_64+0x5b/0x1b0
[1640542.573724] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[1640542.575642] RIP: 0033:0x7f45d6e61e27

James Wang has reproduced it stably on the latest 4.19 LTS.
After some debugging, we finally proved that it's due to ftrace
buffer out-of-bound access using a debug tool as follows:
[ 86.775200] BUG: Out-of-bounds write at addr 0xffff88aefe8b7000
[ 86.780806] no_context+0xdf/0x3c0
[ 86.784327] __do_page_fault+0x252/0x470
[ 86.788367] do_page_fault+0x32/0x140
[ 86.792145] page_fault+0x1e/0x30
[ 86.795576] strncpy_from_unsafe+0x66/0xb0
[ 86.799789] fetch_memory_string+0x25/0x40
[ 86.804002] fetch_deref_string+0x51/0x60
[ 86.808134] kprobe_trace_func+0x32d/0x3a0
[ 86.812347] kprobe_dispatcher+0x45/0x50
[ 86.816385] kprobe_ftrace_handler+0x90/0xf0
[ 86.820779] ftrace_ops_assist_func+0xa1/0x140
[ 86.825340] 0xffffffffc00750bf
[ 86.828603] do_sys_open+0x5/0x1f0
[ 86.832124] do_syscall_64+0x5b/0x1b0
[ 86.835900] entry_SYSCALL_64_after_hwframe+0x44/0xa9

commit b220c049d519 ("tracing: Check length before giving out
the filter buffer") adds length check to protect trace data
overflow introduced in 0fc1b09ff1ff, seems that this fix can't prevent
overflow entirely, the length check should also take the sizeof
entry->array[0] into account, since this array[0] is filled the
length of trace data and occupy addtional space and risk overflow.

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: rastreo: corrija la verificación de longitud que causa corrupción de la memoria. Hemos sufrido fallos graves del kernel debido a la corrupción de la memoria en nuestro entorno de producción, como Call Trace: [1640542.554277] fallo de protección general. : 0000 [#1] SMP PTI [1640542.554856] CPU: 17 PID: 26996 Comm: python Kdump: cargado Contaminado:G [1640542.556629] RIP: 0010:kmem_cache_alloc+0x90/0x190 [1640542.559074] : 0018:ffffb16faa597df8 EFLAGS: 00010286 [ 1640542.559587] RAX: 0000000000000000 RBX: 0000000000400200 RCX: 0000000006e931bf [1640542.560323] RDX: 0000000006e931be RSI: 0000400200 RDI: ffff9a45ff004300 [1640542.560996] RBP: 0000000000400200 R08: 0000000000023420 R09: 0000000000000000 [1640542.561670] : 0000000000000000 R11: 0000000000000000 R12: ffffffff9a20608d [1640542.562366] R13: ffff9a45ff004300 R14: ffff9a45ff004300 R15: 696c662f65636976 [1640542.563128] FS: 00007f45d7c6f740(0000) GS:ffff9a45ff840000(0000) GS:0000000000000000 [1640542.563937] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [1640542.564557] CR2: 00007f45d71311a0 CR3: 000000189d63e004 CR4: 00000000003606e0 [1640542.565279] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [1640542.5 66069] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [1640542.566742] Seguimiento de llamadas: [1640542.567009] anon_vma_clone+0x5d/0x170 2.567417] __split_vma+0x91/0x1a0 [1640542.567777] do_munmap+0x2c6/0x320 [1640542.568128] vm_munmap+0x54/0x70 [1640542.569990] __x64_sys_munmap+0x22/0x30 [1640542.572005] _64+0x5b/0x1b0 [1640542.573724] entrada_SYSCALL_64_after_hwframe+0x44/0xa9 [1640542.575642] RIP: 0033:0x7f45d6e61e27 James Wang lo ha reproducido de forma estable en la última versión 4.19 LTS. Después de algunas depuraciones, finalmente demostramos que se debe al acceso fuera de los límites al búfer ftrace usando una herramienta de depuración de la siguiente manera: [86.775200] ERROR: Escritura fuera de los límites en la dirección 0xffff88aefe8b7000 [86.780806] no_context+0xdf/0x3c0 [86.784327 ] __do_page_fault+0x252/0x470 [ 86.788367] do_page_fault+0x32/0x140 [ 86.792145] page_fault+0x1e/0x30 [ 86.795576] strncpy_from_unsafe+0x66/0xb0 [ 86.799789] ry_string+0x25/0x40 [ 86.804002] fetch_deref_string+0x51/0x60 [ 86.808134] kprobe_trace_func +0x32d/0x3a0 [ 86.812347] kprobe_dispatcher+0x45/0x50 [ 86.816385] kprobe_ftrace_handler+0x90/0xf0 [ 86.820779] ftrace_ops_assist_func+0xa1/0x140 [ 86.825340] ffffc00750bf [ 86.828603] do_sys_open+0x5/0x1f0 [ 86.832124] do_syscall_64+0x5b/0x1b0 [ 86.835900 ] Entry_SYSCALL_64_after_hwframe+0x44/0xa9 commit b220c049d519 ("rastreo: verificar la longitud antes de entregar el búfer de filtro") agrega verificación de longitud para proteger el desbordamiento de datos de seguimiento introducido en 0fc1b09ff1ff, parece que esta solución no puede evitar el desbordamiento por completo, la verificación de longitud también debería tenga en cuenta el tamaño de la entrada->matriz[0], ya que esta matriz[0] ocupa toda la longitud de los datos de seguimiento y ocupa espacio adicional y corre el riesgo de desbordarse.

*Credits: N/A

CVSS Scores

CISAv3.1 9.8

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

* Common Vulnerability Scoring System

SSVC

Decision:Attend

Exploitation

None

Automatable

Yes

Tech. Impact

Total

* Organization's Worst-case Scenario

Timeline

2024-05-21 CVE Reserved
2024-05-21 CVE Published
2024-05-22 EPSS Updated
2024-12-19 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-125: Out-of-bounds Read

CAPEC

References (13)

URL	Tag	Source
https://git.kernel.org/stable/c/2e584b1a02eeb860e286d39bc408b25ebc5ec844	Vuln. Introduced
https://git.kernel.org/stable/c/e46d433754420b4d6513ca389403de88a0910279	Vuln. Introduced
https://git.kernel.org/stable/c/0572fc6a510add9029b113239eaabf4b5bce8ec9	Vuln. Introduced
https://git.kernel.org/stable/c/a0997a86f5c0085e183ddee5fb72091d584d3d16	Vuln. Introduced
https://git.kernel.org/stable/c/7c93d8cff582c459350d6f8906eea6e4cd60d959	Vuln. Introduced
https://git.kernel.org/stable/c/b220c049d5196dd94d992dd2dc8cba1a5e6123bf	Vuln. Introduced

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/edcce01e0e50840a9aa6a70baed21477bdd2c9f9	2021-06-16
https://git.kernel.org/stable/c/2d598902799886d67947406f26ee8e5fd2ca097f	2021-06-16
https://git.kernel.org/stable/c/31ceae385556c37e4d286cb6378696448f566883	2021-06-16
https://git.kernel.org/stable/c/d63f00ec908b3be635ead5d6029cc94246e1f38d	2021-06-16
https://git.kernel.org/stable/c/43c32c22254b9328d7abb1c2b0f689dc67838e60	2021-06-16
https://git.kernel.org/stable/c/b16a249eca2230c2cd66fa1d4b94743bd9b6ef92	2021-06-16
https://git.kernel.org/stable/c/3e08a9f9760f4a70d633c328a76408e62d6f80a3	2021-06-08

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"				>= 4.9.258 < 4.9.273 Search vendor "Linux" for product "Linux Kernel" and version " >= 4.9.258 < 4.9.273"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 4.14.222 < 4.14.237 Search vendor "Linux" for product "Linux Kernel" and version " >= 4.14.222 < 4.14.237"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 4.19.177 < 4.19.195 Search vendor "Linux" for product "Linux Kernel" and version " >= 4.19.177 < 4.19.195"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.4.99 < 5.4.126 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.4.99 < 5.4.126"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.10.17 < 5.10.44 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.10.17 < 5.10.44"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.11 < 5.12.11 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.11 < 5.12.11"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.11 < 5.13 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.11 < 5.13"		en		Affected