Linux Kernel up to 7.0.9 pgtable.c pmd_present locking

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.0.9. It has been rated as critical. This affects the function pmd_present of the file arch/powerpc/mm/book3s64/pgtable.c. Performing a manipulation results in locking. This vulnerability is cataloged as CVE-2026-53108. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 7.0.9. This affects the function pmd_present of the file arch/powerpc/mm/book3s64/pgtable.c. The manipulation with an unknown input leads to a locking vulnerability. CWE is classifying the issue as CWE-667. The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors. This is going to have an impact on availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: powerpc/64s: Fix unmap race with PMD migration entries The following race is possible with migration swap entries or device-private THP entries. e.g. when move_pages is called on a PMD THP page, then there maybe an intermediate state, where PMD entry acts as a migration swap entry (pmd_present() is true). Then if an munmap happens at the same time, then this VM_BUG_ON() can happen in pmdp_huge_get_and_clear_full(). This patch fixes that. Thread A: move_pages() syscall add_folio_for_migration() mmap_read_lock(mm) folio_isolate_lru(folio) mmap_read_unlock(mm) do_move_pages_to_node() migrate_pages() try_to_migrate_one() spin_lock(ptl) set_pmd_migration_entry() pmdp_invalidate() # PMD: _PAGE_INVALID | _PAGE_PTE | pfn set_pmd_at() # PMD: migration swap entry (pmd_present=0) spin_unlock(ptl) [page copy phase] # Thread B: munmap() mmap_write_downgrade(mm) unmap_vmas() -> zap_pmd_range() zap_huge_pmd() __pmd_trans_huge_lock() pmd_is_huge(): # !pmd_present && !pmd_none -> TRUE (swap entry) pmd_lock() -> # spin_lock(ptl), waits for Thread A to release ptl pmdp_huge_get_and_clear_full() VM_BUG_ON(!pmd_present(*pmdp)) # HITS! [ 287.738700][ T1867] ------------[ cut here ]------------ [ 287.743843][ T1867] kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:187! cpu 0x0: Vector: 700 (Program Check) at [c00000044037f4f0] pc: c000000000094ca4: pmdp_huge_get_and_clear_full+0x6c/0x23c lr: c000000000645dec: zap_huge_pmd+0xb0/0x868 sp: c00000044037f790 msr: 800000000282b033 current = 0xc0000004032c1a00 paca = 0xc000000004fe0000 irqmask: 0x03 irq_happened: 0x09 pid = 1867, comm = a.out kernel BUG at :187! Linux version 6.19.0-12136-g14360d4f917c-dirty (powerpc64le-linux-gnu-gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40) #27 SMP PREEMPT Sun Feb 22 10:38:56 IST 2026 enter ? for help [link register ] c000000000645dec zap_huge_pmd+0xb0/0x868 [c00000044037f790] c00000044037f7d0 (unreliable) [c00000044037f7d0] c000000000645dcc zap_huge_pmd+0x90/0x868 [c00000044037f840] c0000000005724cc unmap_page_range+0x176c/0x1f40 [c00000044037fa00] c000000000572ea0 unmap_vmas+0xb0/0x1d8 [c00000044037fa90] c0000000005af254 unmap_region+0xb4/0x128 [c00000044037fb50] c0000000005af400 vms_complete_munmap_vmas+0x138/0x310 [c00000044037fbe0] c0000000005b0f1c do_vmi_align_munmap+0x1ec/0x238 [c00000044037fd30] c0000000005b3688 __vm_munmap+0x170/0x1f8 [c00000044037fdf0] c000000000587f74 sys_munmap+0x2c/0x40 [c00000044037fe10] c000000000032668 system_call_exception+0x128/0x350 [c00000044037fe50] c00000000000d05c system_call_vectored_common+0x15c/0x2ec ---- Exception: 3000 (System Call Vectored) at 0000000010064a2c SP (7fff9b1ee9c0) is in userspace 0:mon> zh commit a30b48bf1b24 ("mm/migrate_device: implement THP migration of zone device pages"), enabled migration for device-private PMD entries. Hence this is one other path where this warning could get trigger from. ------------[ cut here ]------------ WARNING: arch/powerpc/mm/book3s64/hash_pgtable.c:199 at hash__pmd_hugepage_update+0x48/0x284, CPU#3: hmm-tests/1905 Modules linked in: test_hmm CPU: 3 UID: 0 PID: 1905 Comm: hmm-tests Tainted: G B W L N 7.0.0-rc1-01438-g7e2f0ee7581c #21 PREEMPT Tainted: [B]=BAD_PAGE, [W]=WARN, [L]=SOFTLOCKUP, [N]=TEST Hardware name: IBM pSeries (emulated by qemu) POWER10 (architected) 0x801200 0xf000006 of:SLOF,git-ee03ae pSeries NIP [c000000000096b70] hash__pmd_hugepage_update+0x48/0x284 LR [c000000000096e7c] hash__pmdp_huge_get_and_clear+0xd0/0xd4 Call Trace: [c000000604707670] [c000000004e102b8] 0xc000000004e102b8 (unreliable) [c000000604707700] [c00000000064ec3c] set_pmd_migration_entry+0x414/0x498 [c000000604707760] [c00000000063e5a4] migrate_vma_col ---truncated---

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-53108 since 06/09/2026. The exploitability is told to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 7.0.10 eliminates this vulnerability. Applying the patch 829367e55012c053738ebe7db20c4a90d6609ece/bbcbf045d6c778e82b47a35fc8728387708e9a3d 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

• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5
• 7.0.6
• 7.0.7
• 7.0.8
• 7.0.9

License

• open-source

Website

• Vendor: https://www.kernel.org/

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