CVE-2022-48631

ext4: fix bug in extents parsing when eh_entries == 0 and eh_depth > 0

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:

ext4: fix bug in extents parsing when eh_entries == 0 and eh_depth > 0

When walking through an inode extents, the ext4_ext_binsearch_idx() function
assumes that the extent header has been previously validated. However, there
are no checks that verify that the number of entries (eh->eh_entries) is
non-zero when depth is > 0. And this will lead to problems because the
EXT_FIRST_INDEX() and EXT_LAST_INDEX() will return garbage and result in this:

[ 135.245946] ------------[ cut here ]------------
[ 135.247579] kernel BUG at fs/ext4/extents.c:2258!
[ 135.249045] invalid opcode: 0000 [#1] PREEMPT SMP
[ 135.250320] CPU: 2 PID: 238 Comm: tmp118 Not tainted 5.19.0-rc8+ #4
[ 135.252067] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b-rebuilt.opensuse.org 04/01/2014
[ 135.255065] RIP: 0010:ext4_ext_map_blocks+0xc20/0xcb0
[ 135.256475] Code:
[ 135.261433] RSP: 0018:ffffc900005939f8 EFLAGS: 00010246
[ 135.262847] RAX: 0000000000000024 RBX: ffffc90000593b70 RCX: 0000000000000023
[ 135.264765] RDX: ffff8880038e5f10 RSI: 0000000000000003 RDI: ffff8880046e922c
[ 135.266670] RBP: ffff8880046e9348 R08: 0000000000000001 R09: ffff888002ca580c
[ 135.268576] R10: 0000000000002602 R11: 0000000000000000 R12: 0000000000000024
[ 135.270477] R13: 0000000000000000 R14: 0000000000000024 R15: 0000000000000000
[ 135.272394] FS: 00007fdabdc56740(0000) GS:ffff88807dd00000(0000) knlGS:0000000000000000
[ 135.274510] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 135.276075] CR2: 00007ffc26bd4f00 CR3: 0000000006261004 CR4: 0000000000170ea0
[ 135.277952] Call Trace:
[ 135.278635] <TASK>
[ 135.279247] ? preempt_count_add+0x6d/0xa0
[ 135.280358] ? percpu_counter_add_batch+0x55/0xb0
[ 135.281612] ? _raw_read_unlock+0x18/0x30
[ 135.282704] ext4_map_blocks+0x294/0x5a0
[ 135.283745] ? xa_load+0x6f/0xa0
[ 135.284562] ext4_mpage_readpages+0x3d6/0x770
[ 135.285646] read_pages+0x67/0x1d0
[ 135.286492] ? folio_add_lru+0x51/0x80
[ 135.287441] page_cache_ra_unbounded+0x124/0x170
[ 135.288510] filemap_get_pages+0x23d/0x5a0
[ 135.289457] ? path_openat+0xa72/0xdd0
[ 135.290332] filemap_read+0xbf/0x300
[ 135.291158] ? _raw_spin_lock_irqsave+0x17/0x40
[ 135.292192] new_sync_read+0x103/0x170
[ 135.293014] vfs_read+0x15d/0x180
[ 135.293745] ksys_read+0xa1/0xe0
[ 135.294461] do_syscall_64+0x3c/0x80
[ 135.295284] entry_SYSCALL_64_after_hwframe+0x46/0xb0

This patch simply adds an extra check in __ext4_ext_check(), verifying that
eh_entries is not 0 when eh_depth is > 0.

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: corrige error en el análisis de extensiones cuando eh_entries == 0 y eh_ Depth > 0 Al recorrer las extensiones de un inodo, la función ext4_ext_binsearch_idx() asume que el encabezado de la extensión ha sido validado previamente. Sin embargo, no hay comprobaciones que verifiquen que el número de entradas (eh->eh_entries) sea distinto de cero cuando la profundidad es > 0. Y esto generará problemas porque EXT_FIRST_INDEX() y EXT_LAST_INDEX() devolverán basura y darán como resultado esto: [135.245946] ------------[ cortar aquí ]------------ [ 135.247579] ¡ERROR del kernel en fs/ext4/extents.c:2258! [ 135.249045] código de operación no válido: 0000 [#1] SMP PREEMPT [ 135.250320] CPU: 2 PID: 238 Comm: tmp118 No contaminado 5.19.0-rc8+ #4 [ 135.252067] Nombre de hardware: PC estándar QEMU (i440FX + PIIX, 1996) , BIOS rel-1.15.0-0-g2dd4b9b-rebuilt.opensuse.org 01/04/2014 [135.255065] RIP: 0010:ext4_ext_map_blocks+0xc20/0xcb0 [135.256475] Código: [135.261433] RSP: ffffc900005939f8 EFLAGS: 00010246 [ 135.262847] RAX: 0000000000000024 RBX: ffffc90000593b70 RCX: 0000000000000023 [ 135.264765] RDX: ffff8880038e5f10 RSI: 0000000000000000 3 RDI: ffff8880046e922c [ 135.266670] RBP: ffff8880046e9348 R08: 0000000000000001 R09: ffff888002ca580c [ 135.268576] R10: 00000000000002602 R 11: 0000000000000000 R12: 0000000000000024 [ 135.270477 ] R13: 0000000000000000 R14: 0000000000000024 R15: 0000000000000000 [ 135.272394] FS: 00007fdabdc56740(0000) GS:ffff88807dd00000(0000) ) knlGS:0000000000000000 [ 135.274510] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 135.276075] CR2: 00007ffc26bd4f00 CR3 : 0000000006261004 CR4: 0000000000170ea0 [ 135.277952] Seguimiento de llamadas: [ 135.278635] [ 135.279247] ? preempt_count_add+0x6d/0xa0 [135.280358]? ¿percpu_counter_add_batch+0x55/0xb0 [135.281612]? _raw_read_unlock+0x18/0x30 [ 135.282704] ext4_map_blocks+0x294/0x5a0 [ 135.283745] ? xa_load+0x6f/0xa0 [135.284562] ext4_mpage_readpages+0x3d6/0x770 [135.285646] read_pages+0x67/0x1d0 [135.286492] ? folio_add_lru+0x51/0x80 [ 135.287441] page_cache_ra_unbounded+0x124/0x170 [ 135.288510] filemap_get_pages+0x23d/0x5a0 [ 135.289457] ? path_openat+0xa72/0xdd0 [135.290332] filemap_read+0xbf/0x300 [135.291158]? _raw_spin_lock_irqsave+0x17/0x40 [ 135.292192] new_sync_read+0x103/0x170 [ 135.293014] vfs_read+0x15d/0x180 [ 135.293745] ksys_read+0xa1/0xe0 [ 135.294461] do_syscall_64+0x3c/0x80 [ 135.295284] Entry_SYSCALL_64_after_hwframe+0x46/0xb0 Este parche simplemente agrega un verificación adicional en __ext4_ext_check(), verificando que eh_entries no sea 0 cuando eh_ Depth sea > 0.

*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

2024-02-25 CVE Reserved
2024-04-28 CVE Published
2024-04-29 EPSS Updated
2024-08-03 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CAPEC

References (5)

URL	Tag	Source

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/bb7eb3ca4b3b0d2c7872cf1a41c30f5e5bd65df0	2022-09-28
https://git.kernel.org/stable/c/958b0ee23f5ac106e7cc11472b71aa2ea9a033bc	2022-09-28
https://git.kernel.org/stable/c/be4df018c0be5ebecf1ca510feacc23be415cefc	2022-09-28
https://git.kernel.org/stable/c/2f5e9de15e4f55fbf56f22d4a2ce406246cc462d	2022-09-28
https://git.kernel.org/stable/c/29a5b8a137ac8eb410cc823653a29ac0e7b7e1b0	2022-09-22

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"				< 5.4.215 Search vendor "Linux" for product "Linux Kernel" and version " < 5.4.215"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 5.10.146 Search vendor "Linux" for product "Linux Kernel" and version " < 5.10.146"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 5.15.71 Search vendor "Linux" for product "Linux Kernel" and version " < 5.15.71"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 5.19.12 Search vendor "Linux" for product "Linux Kernel" and version " < 5.19.12"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 6.0 Search vendor "Linux" for product "Linux Kernel" and version " < 6.0"		en		Affected