---
cve: "CVE-2024-57877"
severity: "MEDIUM"
cvss: 6.1
epss: "18%"
vendor: "Linux"
kev: false
exploited: false
published: "2025-01-11 15:15:08"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-08-31T04:34:03+02:00"
---

# CVE-2024-57877

> 6.1 MEDIUM

## Beschreibung

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

arm64: ptrace: fix partial SETREGSET for NT_ARM_POE

Currently poe_set() doesn't initialize the temporary 'ctrl' variable,
and a SETREGSET call with a length of zero will leave this
uninitialized. Consequently an arbitrary value will be written back to
target->thread.por_el0, potentially leaking up to 64 bits of memory from
the kernel stack. The read is limited to a specific slot on the stack,
and the issue does not provide a write mechanism.

Fix this by initializing the temporary value before copying the regset
from userspace, as for other regsets (e.g. NT_PRSTATUS, NT_PRFPREG,
NT_ARM_SYSTEM_CALL). In the case of a zero-length write, the existing
contents of POR_EL1 will be retained.

Before this patch:

| # ./poe-test
| Attempting to write NT_ARM_POE::por_el0 = 0x900d900d900d900d
| SETREGSET(nt=0x40f, len=8) wrote 8 bytes
|
| Attempting to read NT_ARM_POE::por_el0
| GETREGSET(nt=0x40f, len=8) read 8 bytes
| Read NT_ARM_POE::por_el0 = 0x900d900d900d900d
|
| Attempting to write NT_ARM_POE (zero length)
| SETREGSET(nt=0x40f, len=0) wrote 0 bytes
|
| Attempting to read NT_ARM_POE::por_el0
| GETREGSET(nt=0x40f, len=8) read 8 bytes
| Read NT_ARM_POE::por_el0 = 0xffff8000839c3d50

After this patch:

| # ./poe-test
| Attempting to write NT_ARM_POE::por_el0 = 0x900d900d900d900d
| SETREGSET(nt=0x40f, len=8) wrote 8 bytes
|
| Attempting to read NT_ARM_POE::por_el0
| GETREGSET(nt=0x40f, len=8) read 8 bytes
| Read NT_ARM_POE::por_el0 = 0x900d900d900d900d
|
| Attempting to write NT_ARM_POE (zero length)
| SETREGSET(nt=0x40f, len=0) wrote 0 bytes
|
| Attempting to read NT_ARM_POE::por_el0
| GETREGSET(nt=0x40f, len=8) read 8 bytes
| Read NT_ARM_POE::por_el0 = 0x900d900d900d900d

## CVSS-Vektor

```
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Gering | warn |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 6.12.5

## Referenzen

- <https://git.kernel.org/stable/c/4105dd76bc8ad6529d47157ef0565cb84ca6676c>
- <https://git.kernel.org/stable/c/594bfc4947c4fcabba1318d8384c61a29a6b89fb>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2024-57877) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_