n the Linux kernel, the following vulnerability has been resolved: x86/fpu: Fix NULL dereference in avx512_status() Problem ------- With CONFIG_X86_DEBUG_FPU enabled, reading /proc/[kthread]/arch_status causes a warning and a NULL pointer dereference. This is because the AVX-512 timestamp code uses x86_task_fpu() but doesn't check it for NULL. CONFIG_X86_DEBUG_FPU addles that function for kernel threads (PF_KTHREAD specifically), making it return NULL. The point of the warning was to ensure that kernel threads only access task->fpu after going through kernel_fpu_begin()/_end(). Note: all kernel tasks exposed in /proc have a valid task->fpu. Solution -------- One option is to silence the warning and check for NULL from x86_task_fpu(). However, that warning is fairly fresh and seems like a defense against misuse of the FPU state in kernel threads. Instead, stop outputting AVX-512_elapsed_ms for kernel threads altogether. The data was garbage anyway because avx512_timestamp is only updated for user threads, not kernel threads. If anyone ever wants to track kernel thread AVX-512 use, they can come back later and do it properly, separate from this bug fix. [ dhansen: mostly rewrite changelog ]
Configuration 1 (hide)
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24 Nov 2025, 19:47
| Type | Values Removed | Values Added |
|---|---|---|
| First Time |
Linux linux Kernel
Linux |
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| CWE | CWE-476 | |
| CPE | cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
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| References | () https://git.kernel.org/stable/c/2ca887e81095b99d890a8878841f36f4920181e6 - Patch | |
| References | () https://git.kernel.org/stable/c/31cd31c9e17ece125aad27259501a2af69ccb020 - Patch | |
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 5.5 |
05 Sep 2025, 17:47
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Published : 2025-09-04 16:15
Updated : 2025-11-24 19:47
NVD link : CVE-2025-38689
Mitre link : CVE-2025-38689
CVE.ORG link : CVE-2025-38689
JSON object : View
NULL Pointer Dereference