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🛡️ CVE-2023-52499 — kernel

🟡 CVSS 5.5 — Medium ✅ No Known Exploit NVD
5.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

powerpc/47x: Fix 47x syscall return crash

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

powerpc/47x: Fix 47x syscall return crash

Eddie reported that newer kernels were crashing during boot on his 476

FSP2 system:

kernel tried to execute user page (b7ee2000) - exploit attempt? (uid: 0)

BUG: Unable to handle kernel instruction fetch

Faulting instruction address: 0xb7ee2000

Oops: Kernel access of bad area, sig: 11 [#1]

BE PAGE_SIZE=4K FSP-2

Modules linked in:

CPU: 0 PID: 61 Comm: mount Not tainted 6.1.55-d23900f.ppcnf-fsp2 #1

Hardware name: ibm,fsp2 476fpe 0x7ff520c0 FSP-2

NIP:  b7ee2000 LR: 8c008000 CTR: 00000000

REGS: bffebd83 TRAP: 0400   Not tainted (6.1.55-d23900f.ppcnf-fs p2)

MSR:  00000030 <IR,DR>  CR: 00001000  XER: 20000000

GPR00: c00110ac bffebe63 bffebe7e bffebe88 8c008000 00001000 00000d12 b7ee2000

GPR08: 00000033 00000000 00000000 c139df10 48224824 1016c314 10160000 00000000

GPR16: 10160000 10160000 00000008 00000000 10160000 00000000 10160000 1017f5b0

GPR24: 1017fa50 1017f4f0 1017fa50 1017f740 1017f630 00000000 00000000 1017f4f0

NIP [b7ee2000] 0xb7ee2000

LR [8c008000] 0x8c008000

Call Trace:

Instruction dump:

XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX

XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX

---[ end trace 0000000000000000 ]---

The problem is in ret_from_syscall where the check for

icache_44x_need_flush is done. When the flush is needed the code jumps

out-of-line to do the flush, and then intends to jump back to continue

the syscall return.

However the branch back to label 1b doesn't return to the correct

location, instead branching back just prior to the return to userspace,

causing bogus register values to be used by the rfi.

The breakage was introduced by commit 6f76a01173cc

("powerpc/syscall: implement system call entry/exit logic in C for PPC32") which

inadvertently removed the "1" label and reused it elsewhere.

Fix it by adding named local labels in the correct locations. Note that

the return label needs to be outside the ifdef so that CONFIG_PPC_47x=n

compiles.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Affected software

CVE-2023-52499 is recorded against 2 packages.

  • kernel (from 6.2.0 up to 6.5.8)
  • linux-kernel

Timeline and source

Published on 2 March 2024 and last revised on 12 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

Other advisories for this package

kernel has other advisories on record. If you are patching this one, these are worth checking on the same host:

CVE-2023-52499 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Medium
CVSS Score 5.5
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2024-03-02
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 6.2.0 6.5.8
linux-kernel — —

Similar Threats

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