CVE-2023-52750

arm64: Restrict CPU_BIG_ENDIAN to GNU as or LLVM IAS 15.x or newer

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:

arm64: Restrict CPU_BIG_ENDIAN to GNU as or LLVM IAS 15.x or newer

Prior to LLVM 15.0.0, LLVM's integrated assembler would incorrectly
byte-swap NOP when compiling for big-endian, and the resulting series of
bytes happened to match the encoding of FNMADD S21, S30, S0, S0.

This went unnoticed until commit:

34f66c4c4d5518c1 ("arm64: Use a positive cpucap for FP/SIMD")

Prior to that commit, the kernel would always enable the use of FPSIMD
early in boot when __cpu_setup() initialized CPACR_EL1, and so usage of
FNMADD within the kernel was not detected, but could result in the
corruption of user or kernel FPSIMD state.

After that commit, the instructions happen to trap during boot prior to
FPSIMD being detected and enabled, e.g.

| Unhandled 64-bit el1h sync exception on CPU0, ESR 0x000000001fe00000 -- ASIMD
| CPU: 0 PID: 0 Comm: swapper Not tainted 6.6.0-rc3-00013-g34f66c4c4d55 #1
| Hardware name: linux,dummy-virt (DT)
| pstate: 400000c9 (nZcv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
| pc : __pi_strcmp+0x1c/0x150
| lr : populate_properties+0xe4/0x254
| sp : ffffd014173d3ad0
| x29: ffffd014173d3af0 x28: fffffbfffddffcb8 x27: 0000000000000000
| x26: 0000000000000058 x25: fffffbfffddfe054 x24: 0000000000000008
| x23: fffffbfffddfe000 x22: fffffbfffddfe000 x21: fffffbfffddfe044
| x20: ffffd014173d3b70 x19: 0000000000000001 x18: 0000000000000005
| x17: 0000000000000010 x16: 0000000000000000 x15: 00000000413e7000
| x14: 0000000000000000 x13: 0000000000001bcc x12: 0000000000000000
| x11: 00000000d00dfeed x10: ffffd414193f2cd0 x9 : 0000000000000000
| x8 : 0101010101010101 x7 : ffffffffffffffc0 x6 : 0000000000000000
| x5 : 0000000000000000 x4 : 0101010101010101 x3 : 000000000000002a
| x2 : 0000000000000001 x1 : ffffd014171f2988 x0 : fffffbfffddffcb8
| Kernel panic - not syncing: Unhandled exception
| CPU: 0 PID: 0 Comm: swapper Not tainted 6.6.0-rc3-00013-g34f66c4c4d55 #1
| Hardware name: linux,dummy-virt (DT)
| Call trace:
| dump_backtrace+0xec/0x108
| show_stack+0x18/0x2c
| dump_stack_lvl+0x50/0x68
| dump_stack+0x18/0x24
| panic+0x13c/0x340
| el1t_64_irq_handler+0x0/0x1c
| el1_abort+0x0/0x5c
| el1h_64_sync+0x64/0x68
| __pi_strcmp+0x1c/0x150
| unflatten_dt_nodes+0x1e8/0x2d8
| __unflatten_device_tree+0x5c/0x15c
| unflatten_device_tree+0x38/0x50
| setup_arch+0x164/0x1e0
| start_kernel+0x64/0x38c
| __primary_switched+0xbc/0xc4

Restrict CONFIG_CPU_BIG_ENDIAN to a known good assembler, which is
either GNU as or LLVM's IAS 15.0.0 and newer, which contains the linked
commit.

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: arm64: restringe CPU_BIG_ENDIAN a GNU como o LLVM IAS 15.x o posterior. Antes de LLVM 15.0.0, el ensamblador integrado de LLVM intercambiaba bytes incorrectamente con NOP al compilar para big-endian. y la serie de bytes resultante coincidió con la codificación de FNMADD S21, S30, S0, S0. Esto pasó desapercibido hasta la confirmación: 34f66c4c4d5518c1 ("arm64: use un cpucap positivo para FP/SIMD") Antes de esa confirmación, el kernel siempre habilitaba el uso de FPSIMD al principio del arranque cuando __cpu_setup() inicializaba CPACR_EL1, y por lo tanto el uso de FNMADD dentro del kernel no se detectó, pero podría provocar la corrupción del estado FPSIMD del usuario o del kernel. Después de esa confirmación, las instrucciones se bloquean durante el arranque antes de que se detecte y habilite FPSIMD, por ejemplo | Excepción de sincronización el1h de 64 bits no controlada en CPU0, ESR 0x000000001fe00000 - ASIMD | CPU: 0 PID: 0 Comunicaciones: intercambiador No contaminado 6.6.0-rc3-00013-g34f66c4c4d55 #1 | Nombre del hardware: linux,dummy-virt (DT) | pstate: 400000c9 (nZcv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) | ordenador personal: __pi_strcmp+0x1c/0x150 | lr: poblar_properties+0xe4/0x254 | sp: ffffd014173d3ad0 | x29: ffffd014173d3af0 x28: ffffbfffddffcb8 x27: 0000000000000000 | x26: 0000000000000058 x25: ffffbfffddfe054 x24: 0000000000000008 | x23: ffffbffffddfe000 x22: ffffbfffddfe000 x21: ffffbfffddfe044 | x20: ffffd014173d3b70 x19: 0000000000000001 x18: 0000000000000005 | x17: 0000000000000010 x16: 0000000000000000 x15: 00000000413e7000 | x14: 0000000000000000 x13: 0000000000001bcc x12: 0000000000000000 | x11: 00000000d00dfeed x10: ffffd414193f2cd0 x9: 0000000000000000 | x8: 0101010101010101 x7: ffffffffffffffc0 x6: 0000000000000000 | x5: 0000000000000000 x4: 0101010101010101 x3: 000000000000002a | x2: 0000000000000001 x1: ffffd014171f2988 x0: ffffbfffddffcb8 | Pánico del kernel: no se sincroniza: excepción no controlada | CPU: 0 PID: 0 Comunicaciones: intercambiador No contaminado 6.6.0-rc3-00013-g34f66c4c4d55 #1 | Nombre del hardware: linux,dummy-virt (DT) | Rastreo de llamadas: | dump_backtrace+0xec/0x108 | show_stack+0x18/0x2c | dump_stack_lvl+0x50/0x68 | dump_stack+0x18/0x24 | pánico+0x13c/0x340 | el1t_64_irq_handler+0x0/0x1c | el1_abort+0x0/0x5c | el1h_64_sync+0x64/0x68 | __pi_strcmp+0x1c/0x150 | unflatten_dt_nodes+0x1e8/0x2d8 | __unflatten_device_tree+0x5c/0x15c | unflatten_device_tree+0x38/0x50 | setup_arch+0x164/0x1e0 | start_kernel+0x64/0x38c | __primary_switched+0xbc/0xc4 Restrinja CONFIG_CPU_BIG_ENDIAN a un buen ensamblador conocido, que sea GNU o LLVM's IAS 15.0.0 y posteriores, que contiene la confirmación vinculada.

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

CWE

CAPEC

References (6)

URL	Tag	Source

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/d08a1e75253b4e19ae290b1c35349f12cfcebc0a	2023-11-28
https://git.kernel.org/stable/c/936c9c10efaefaf1ab3ef020e1f8aaaaff1ad2f9	2023-11-28
https://git.kernel.org/stable/c/ef0224ee5399ea8a46bc07dc6c6494961ed5fdd2	2023-11-28
https://git.kernel.org/stable/c/bd31e534721ab95ef237020fe6995c899ffdf21a	2023-11-28
https://git.kernel.org/stable/c/69e619d2fd056fe1f5d0adf01584f2da669e0d28	2023-11-28
https://git.kernel.org/stable/c/146a15b873353f8ac28dc281c139ff611a3c4848	2023-10-26

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"				< 5.10.202 Search vendor "Linux" for product "Linux Kernel" and version " < 5.10.202"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 5.15.140 Search vendor "Linux" for product "Linux Kernel" and version " < 5.15.140"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 6.1.64 Search vendor "Linux" for product "Linux Kernel" and version " < 6.1.64"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 6.5.13 Search vendor "Linux" for product "Linux Kernel" and version " < 6.5.13"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 6.6.3 Search vendor "Linux" for product "Linux Kernel" and version " < 6.6.3"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 6.7 Search vendor "Linux" for product "Linux Kernel" and version " < 6.7"		en		Affected