Описание
In the Linux kernel, the following vulnerability has been resolved:
arm64: mm: fix VA-range sanity check
Both create_mapping_noalloc() and update_mapping_prot() sanity-check
their 'virt' parameter, but the check itself doesn't make much sense.
The condition used today appears to be a historical accident.
The sanity-check condition:
if ((virt >= PAGE_END) && (virt < VMALLOC_START)) {
[ ... warning here ... ]
return;
}
... can only be true for the KASAN shadow region or the module region,
and there's no reason to exclude these specifically for creating and
updateing mappings.
When arm64 support was first upstreamed in commit:
c1cc1552616d0f35 ("arm64: MMU initialisation")
... the condition was:
if (virt < VMALLOC_START) {
[ ... warning here ... ]
return;
}
At the time, VMALLOC_START was the lowest kernel address, and this was
checking whether 'virt' would be translated via TTBR1.
Subsequently in commit:
14c127c957c1c607 ("arm64: mm: Flip kernel VA space")
... the condition was changed to:
if ((virt >= VA_START) && (virt < VMALLOC_START)) {
[ ... warning here ... ]
return;
}
This appear to have been a thinko. The commit moved the linear map to
the bottom of the kernel address space, with VMALLOC_START being at the
halfway point. The old condition would warn for changes to the linear
map below this, and at the time VA_START was the end of the linear map.
Subsequently we cleaned up the naming of VA_START in commit:
77ad4ce69321abbe ("arm64: memory: rename VA_START to PAGE_END")
... keeping the erroneous condition as:
if ((virt >= PAGE_END) && (virt < VMALLOC_START)) {
[ ... warning here ... ]
return;
}
Correct the condition to check against the start of the TTBR1 address
space, which is currently PAGE_OFFSET. This simplifies the logic, and
more clearly matches the "outside kernel range" message in the warning.
A logic flaw was found in the Linux kernel's arm64 memory management subsystem. The virtual address range sanity check in create_mapping_noalloc() and update_mapping_prot() uses an incorrect condition that only excludes the KASAN shadow region and module region, rather than properly validating addresses translated via TTBR1. This check was the result of historical code changes that inadvertently introduced an erroneous condition.
Отчет
This is a code correctness fix for arm64 architecture that addresses an incorrect sanity check condition. The flawed check does not create an exploitable vulnerability in practice, as the affected code paths are used during kernel initialization and memory mapping operations that require privileged access. The fix simplifies the logic to properly validate kernel address ranges.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Not affected | ||
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Fix deferred | ||
| Red Hat Enterprise Linux 8 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2025:6966 | 13.05.2025 |
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2025:6966 | 13.05.2025 |
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Дополнительная информация
Статус:
EPSS
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: arm64: mm: fix VA-range sanity check Both create_mapping_noalloc() and update_mapping_prot() sanity-check their 'virt' parameter, but the check itself doesn't make much sense. The condition used today appears to be a historical accident. The sanity-check condition: if ((virt >= PAGE_END) && (virt < VMALLOC_START)) { [ ... warning here ... ] return; } ... can only be true for the KASAN shadow region or the module region, and there's no reason to exclude these specifically for creating and updateing mappings. When arm64 support was first upstreamed in commit: c1cc1552616d0f35 ("arm64: MMU initialisation") ... the condition was: if (virt < VMALLOC_START) { [ ... warning here ... ] return; } At the time, VMALLOC_START was the lowest kernel address, and this was checking whether 'virt' would be translated via TTBR1. Subsequently in commit: 14c127c957c1c607 ("arm64: mm: Flip kernel VA space") ... the condition was changed...
In the Linux kernel, the following vulnerability has been resolved: arm64: mm: fix VA-range sanity check Both create_mapping_noalloc() and update_mapping_prot() sanity-check their 'virt' parameter, but the check itself doesn't make much sense. The condition used today appears to be a historical accident. The sanity-check condition: if ((virt >= PAGE_END) && (virt < VMALLOC_START)) { [ ... warning here ... ] return; } ... can only be true for the KASAN shadow region or the module region, and there's no reason to exclude these specifically for creating and updateing mappings. When arm64 support was first upstreamed in commit: c1cc1552616d0f35 ("arm64: MMU initialisation") ... the condition was: if (virt < VMALLOC_START) { [ ... warning here ... ] return; } At the time, VMALLOC_START was the lowest kernel address, and this was checking whether 'virt' would be translated via TTBR1. Subsequently in commit: 14c127c957c1c607 ("arm64: mm: Flip kernel VA space") ...
In the Linux kernel, the following vulnerability has been resolved: a ...
In the Linux kernel, the following vulnerability has been resolved: arm64: mm: fix VA-range sanity check Both create_mapping_noalloc() and update_mapping_prot() sanity-check their 'virt' parameter, but the check itself doesn't make much sense. The condition used today appears to be a historical accident. The sanity-check condition: if ((virt >= PAGE_END) && (virt < VMALLOC_START)) { [ ... warning here ... ] return; } ... can only be true for the KASAN shadow region or the module region, and there's no reason to exclude these specifically for creating and updateing mappings. When arm64 support was first upstreamed in commit: c1cc1552616d0f35 ("arm64: MMU initialisation") ... the condition was: if (virt < VMALLOC_START) { [ ... warning here ... ] return; } At the time, VMALLOC_START was the lowest kernel address, and this was checking whether 'virt' would be translated via TTBR1. Subsequently in commit: 14c127c957c1c607 ("arm64: mm: Flip kernel VA space") ...
EPSS
5.5 Medium
CVSS3