CVE-2021-47256

mm/memory-failure: make sure wait for page writeback in memory_failure

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:

mm/memory-failure: make sure wait for page writeback in memory_failure

Our syzkaller trigger the "BUG_ON(!list_empty(&inode->i_wb_list))" in
clear_inode:

kernel BUG at fs/inode.c:519!
Internal error: Oops - BUG: 0 [#1] SMP
Modules linked in:
Process syz-executor.0 (pid: 249, stack limit = 0x00000000a12409d7)
CPU: 1 PID: 249 Comm: syz-executor.0 Not tainted 4.19.95
Hardware name: linux,dummy-virt (DT)
pstate: 80000005 (Nzcv daif -PAN -UAO)
pc : clear_inode+0x280/0x2a8
lr : clear_inode+0x280/0x2a8
Call trace:
clear_inode+0x280/0x2a8
ext4_clear_inode+0x38/0xe8
ext4_free_inode+0x130/0xc68
ext4_evict_inode+0xb20/0xcb8
evict+0x1a8/0x3c0
iput+0x344/0x460
do_unlinkat+0x260/0x410
__arm64_sys_unlinkat+0x6c/0xc0
el0_svc_common+0xdc/0x3b0
el0_svc_handler+0xf8/0x160
el0_svc+0x10/0x218
Kernel panic - not syncing: Fatal exception

A crash dump of this problem show that someone called __munlock_pagevec
to clear page LRU without lock_page: do_mmap -> mmap_region -> do_munmap
-> munlock_vma_pages_range -> __munlock_pagevec.

As a result memory_failure will call identify_page_state without
wait_on_page_writeback. And after truncate_error_page clear the mapping
of this page. end_page_writeback won't call sb_clear_inode_writeback to
clear inode->i_wb_list. That will trigger BUG_ON in clear_inode!

Fix it by checking PageWriteback too to help determine should we skip
wait_on_page_writeback.

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mm/memory-failure: asegúrese de esperar la reescritura de la página en Memory_failure. Nuestro syzkaller activa el "BUG_ON(!list_empty(&inode->i_wb_list))" en clear_inode: kernel BUG en fs /inodo.c:519! Error interno: Oops - BUG: 0 [#1] Módulos SMP vinculados en: Proceso syz-executor.0 (pid: 249, límite de pila = 0x00000000a12409d7) CPU: 1 PID: 249 Comm: syz-executor.0 No contaminado 4.19. 95 Nombre de hardware: linux,dummy-virt (DT) pstate: 80000005 (Nzcv daif -PAN -UAO) pc: clear_inode+0x280/0x2a8 lr: clear_inode+0x280/0x2a8 Rastreo de llamadas: clear_inode+0x280/0x2a8 ext4_clear_inode+0x38/0xe8 ext4_free_inode+0x130/0xc68 ext4_evict_inode+0xb20/0xcb8 desalojar+0x1a8/0x3c0 iput+0x344/0x460 do_unlinkat+0x260/0x410 __arm64_sys_unlinkat+0x6c/0xc0 el0_svc_common+0xdc /0x3b0 el0_svc_handler+0xf8/0x160 el0_svc+0x10/0x218 Pánico del kernel: no se sincroniza : Excepción fatal Un volcado de memoria de este problema muestra que alguien llamó a __munlock_pagevec para borrar la página LRU sin lock_page: do_mmap -> mmap_region -> do_munmap -> munlock_vma_pages_range -> __munlock_pagevec. Como resultado, Memory_failure llamará a identify_page_state sin wait_on_page_writeback. Y después de truncate_error_page, borre el mapeo de esta página. end_page_writeback no llamará a sb_clear_inode_writeback para borrar inode->i_wb_list. ¡Eso activará BUG_ON en clear_inode! Solucionarlo marcando también PageWriteback para ayudar a determinar si debemos omitir wait_on_page_writeback.

*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

2024-04-10 CVE Reserved
2024-05-21 CVE Published
2024-05-22 EPSS Updated
2024-09-11 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CAPEC

References (7)

URL	Tag	Source
https://git.kernel.org/stable/c/0bc1f8b0682caa39f45ce1e0228ebf43acb46111	Vuln. Introduced

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/d05267fd27a5c4f54e06daefa3035995d765ca0c	2021-06-30
https://git.kernel.org/stable/c/6d210d547adc2218ef8b5bcf23518c5f2f1fd872	2021-06-30
https://git.kernel.org/stable/c/566345aaabac853aa866f53a219c4b02a6beb527	2021-06-23
https://git.kernel.org/stable/c/9e379da727a7a031be9b877cde7b9c34a0fb8306	2021-06-23
https://git.kernel.org/stable/c/28788dc5c70597395b6b451dae4549bbaa8e2c56	2021-06-23
https://git.kernel.org/stable/c/e8675d291ac007e1c636870db880f837a9ea112a	2021-06-16

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"				>= 3.16 < 4.14.238 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.16 < 4.14.238"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 3.16 < 4.19.196 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.16 < 4.19.196"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 3.16 < 5.4.128 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.16 < 5.4.128"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 3.16 < 5.10.46 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.16 < 5.10.46"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 3.16 < 5.12.13 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.16 < 5.12.13"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 3.16 < 5.13 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.16 < 5.13"		en		Affected