Linux Kernel up to 7.1.5/7.2-rc4 Device-Private PMD mm/page_vma_mapped.c page_vma_mapped_walk memory corruption

Summaryinfo

A vulnerability has been found in Linux Kernel up to 7.1.5/7.2-rc4 and classified as very critical. This impacts the function page_vma_mapped_walk of the file mm/page_vma_mapped.c of the component Device-Private PMD Handler. Performing a manipulation results in memory corruption. This vulnerability is known as CVE-2026-68163. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability classified as very critical has been found in Linux Kernel up to 7.1.5/7.2-rc4. This affects the function page_vma_mapped_walk of the file mm/page_vma_mapped.c of the component Device-Private PMD Handler. The manipulation with an unknown input leads to a memory corruption vulnerability. CWE is classifying the issue as CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: mm/page_vma_mapped: fix device-private PMD handling Commit 65edfda6f3f2 ("mm/rmap: extend rmap and migration support device-private entries") introduced the concept of device-private PMD entries, but did not correctly update the rmap walk code to account for them. As a result, when page_vma_mapped_walk() encounters device-private PMD entries, it takes no action other than to acquire the PMD lock and exit. However this is highly problematic for two reasons - firstly, device private entries possess a PFN so check_pmd() needs to be called to ensure an overlapping PFN range. Secondly, and more importantly, if PVMW_MIGRATION is set the caller assumes the returned entry is a migration entry, resulting in memory corruption when the caller tries to interpret the device private entry as such. In addition, commit 146287290023 ("mm/huge_memory: implement device-private THP splitting") allowed device private PMDs to be split like THP mappings, but again did not update this code path. As a result, we might race a PMD split prior to acquiring the PMD lock. This patch addresses all of these issues by invoking check_pmd(), ensuring PMVW_MIGRATION is not set and checks whether a split raced us we do for PMD THP and migration entries. Instead of checking for a subset of the cases after taking the pmd_lock(), put device-private along with pmd_trans_huge() and pmd_is_migration_entry(). Also remove thp_migration_supported() as it is already guarded by pmd_is_migration_entry(). [[email protected]: fix Raspberry Pi 1 build, per David]

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-68163 since 07/30/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/10/2026).

Upgrading to version 7.1.6 or 7.2-rc5 eliminates this vulnerability. Applying the patch ab6209f4b48a98ef14d6766acdb62aa9bb32e670/f84ca9b1888d8fce7dfefe0e750fa971f8797486 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4
• 7.1.5
• 7.2-rc1
• 7.2-rc2
• 7.2-rc3
• 7.2-rc4

License

• open-source

Website

• Vendor: https://www.kernel.org/

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