CVE-2025-21866

/// Technical description

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

powerpc/code-patching: Fix KASAN hit by not flagging text patching area as VM_ALLOC

Erhard reported the following KASAN hit while booting his PowerMac G4

with a KASAN-enabled kernel 6.13-rc6:

BUG: KASAN: vmalloc-out-of-bounds in copy_to_kernel_nofault+0xd8/0x1c8

Write of size 8 at addr f1000000 by task chronyd/1293

CPU: 0 UID: 123 PID: 1293 Comm: chronyd Tainted: G W 6.13.0-rc6-PMacG4 #2

Tainted: [W]=WARN

Hardware name: PowerMac3,6 7455 0x80010303 PowerMac

Call Trace:

[c2437590] [c1631a84] dump_stack_lvl+0x70/0x8c (unreliable)

[c24375b0] [c0504998] print_report+0xdc/0x504

[c2437610] [c050475c] kasan_report+0xf8/0x108

[c2437690] [c0505a3c] kasan_check_range+0x24/0x18c

[c24376a0] [c03fb5e4] copy_to_kernel_nofault+0xd8/0x1c8

[c24376c0] [c004c014] patch_instructions+0x15c/0x16c

[c2437710] [c00731a8] bpf_arch_text_copy+0x60/0x7c

[c2437730] [c0281168] bpf_jit_binary_pack_finali

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References