Linux Kernel up to 5.10.101/5.15.24/5.16.10 COW Page do_wp_page permission

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 5.10.101/5.15.24/5.16.10. The impacted element is the function do_wp_page of the component COW Page Handler. This manipulation causes permission. This vulnerability is tracked as CVE-2022-48797. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 5.10.101/5.15.24/5.16.10 and classified as critical. Affected by this vulnerability is the function do_wp_page of the component COW Page Handler. The manipulation with an unknown input leads to a permission vulnerability. The CWE definition for the vulnerability is CWE-275. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2022-48797 since 07/16/2024. The exploitation appears to be easy. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/03/2025). MITRE ATT&CK project uses the attack technique T1222 for this issue.

Upgrading to version 5.10.102, 5.15.25 or 5.16.11 eliminates this vulnerability. Applying the patch 254090925e16/b3dc4b9d3ca6/d187eeb02d18/80d47f5de5e3 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.10.101
• 5.15.0
• 5.15.1
• 5.15.2
• 5.15.3
• 5.15.4
• 5.15.5
• 5.15.6
• 5.15.7
• 5.15.8
• 5.15.9
• 5.15.10
• 5.15.11
• 5.15.12
• 5.15.13
• 5.15.14
• 5.15.15
• 5.15.16
• 5.15.17
• 5.15.18
• 5.15.19
• 5.15.20
• 5.15.21
• 5.15.22
• 5.15.23
• 5.15.24
• 5.16.0
• 5.16.1
• 5.16.2
• 5.16.3
• 5.16.4
• 5.16.5
• 5.16.6
• 5.16.7
• 5.16.8
• 5.16.9
• 5.16.10

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

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