Описание
In the Linux kernel, the following vulnerability has been resolved:
mm: don't try to NUMA-migrate COW pages that have other uses
Oded Gabbay reports that enabling NUMA balancing causes corruption with
his Gaudi accelerator test load:
"All the details are in the bug, but the bottom line is that somehow,
this patch causes corruption when the numa balancing feature is
enabled AND we don't use process affinity AND we use GUP to pin pages
so our accelerator can DMA to/from system memory.
Either disabling numa balancing, using process affinity to bind to
specific numa-node or reverting this patch causes the bug to
disappear"
and Oded bisected the issue to commit 09854ba94c6a ("mm: do_wp_page()
simplification").
Now, the NUMA balancing shouldn't actually be changing the writability
of a page, and as such shouldn't matter for COW. But it appears it
does. Suspicious.
However, regardless of that, the condition for enabling NUMA faults in
change_pte_range() is nonsensical. It uses "page_mapcount(page)" to
decide if a COW page should be NUMA-protected or not, and that makes
absolutely no sense.
The number of mappings a page has is irrelevant: not only does GUP get a
reference to a page as in Oded's case, but the other mappings migth be
paged out and the only reference to them would be in the page count.
Since we should never try to NUMA-balance a page that we can't move
anyway due to other references, just fix the code to use 'page_count()'.
Oded confirms that that fixes his issue.
Now, this does imply that something in NUMA balancing ends up changing
page protections (other than the obvious one of making the page
inaccessible to get the NUMA faulting information). Otherwise the COW
simplification wouldn't matter - since doing the GUP on the page would
make sure it's writable.
The cause of that permission change would be good to figure out too,
since it clearly results in spurious COW events - but fixing the
nonsensical test that just happened to work before is obviously the
CorrectThing(tm) to do regardless.
A vulnerability was found in the Linux kernel's memory management system, where the change_pte_range() function improperly attempts to NUMA-migrate Copy-On-Write pages with existing references. This occurs due to an incorrect check using page_mapcount, leading to potential corruption when NUMA balancing is enabled without process affinity. The impact of this vulnerability can result in data corruption during DMA operations, affecting system reliability.
Меры по смягчению последствий
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Out of support scope | ||
| Red Hat Enterprise Linux 8 | kernel | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel | Will not fix | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Will not fix |
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Дополнительная информация
Статус:
EPSS
5.1 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: mm: don't try to NUMA-migrate COW pages that have other uses Oded Gabbay reports that enabling NUMA balancing causes corruption with his Gaudi accelerator test load: "All the details are in the bug, but the bottom line is that somehow, this patch causes corruption when the numa balancing feature is enabled AND we don't use process affinity AND we use GUP to pin pages so our accelerator can DMA to/from system memory. Either disabling numa balancing, using process affinity to bind to specific numa-node or reverting this patch causes the bug to disappear" and Oded bisected the issue to commit 09854ba94c6a ("mm: do_wp_page() simplification"). Now, the NUMA balancing shouldn't actually be changing the writability of a page, and as such shouldn't matter for COW. But it appears it does. Suspicious. However, regardless of that, the condition for enabling NUMA faults in change_pte_range() is nonsensical. It uses "page_map...
In the Linux kernel, the following vulnerability has been resolved: mm: don't try to NUMA-migrate COW pages that have other uses Oded Gabbay reports that enabling NUMA balancing causes corruption with his Gaudi accelerator test load: "All the details are in the bug, but the bottom line is that somehow, this patch causes corruption when the numa balancing feature is enabled AND we don't use process affinity AND we use GUP to pin pages so our accelerator can DMA to/from system memory. Either disabling numa balancing, using process affinity to bind to specific numa-node or reverting this patch causes the bug to disappear" and Oded bisected the issue to commit 09854ba94c6a ("mm: do_wp_page() simplification"). Now, the NUMA balancing shouldn't actually be changing the writability of a page, and as such shouldn't matter for COW. But it appears it does. Suspicious. However, regardless of that, the condition for enabling NUMA faults in change_pte_range() is nonsensical.
In the Linux kernel, the following vulnerability has been resolved: m ...
In the Linux kernel, the following vulnerability has been resolved: mm: don't try to NUMA-migrate COW pages that have other uses Oded Gabbay reports that enabling NUMA balancing causes corruption with his Gaudi accelerator test load: "All the details are in the bug, but the bottom line is that somehow, this patch causes corruption when the numa balancing feature is enabled AND we don't use process affinity AND we use GUP to pin pages so our accelerator can DMA to/from system memory. Either disabling numa balancing, using process affinity to bind to specific numa-node or reverting this patch causes the bug to disappear" and Oded bisected the issue to commit 09854ba94c6a ("mm: do_wp_page() simplification"). Now, the NUMA balancing shouldn't actually be changing the writability of a page, and as such shouldn't matter for COW. But it appears it does. Suspicious. However, regardless of that, the condition for enabling NUMA faults in change_pte_range() is nonsensical...
Уязвимость компонента mm ядра операционной системы Linux, позволяющая нарушителю вызвать отказ в обслуживании
EPSS
5.1 Medium
CVSS3