7.8

CVE-2026-31787

xen/privcmd: fix double free via VMA splitting

In the Linux kernel, the following vulnerability has been resolved:

xen/privcmd: fix double free via VMA splitting

privcmd_vm_ops defines .close (privcmd_close), but neither .may_split
nor .open. When userspace does a partial munmap() on a privcmd mapping,
the kernel splits the VMA via __split_vma(). Since may_split is NULL,
the split is allowed. vm_area_dup() copies vm_private_data (a pages
array allocated in alloc_empty_pages()) into the new VMA without any
fixup, because there is no .open callback.

Both VMAs now point to the same pages array. When the unmapped portion
is closed, privcmd_close() calls:
    - xen_unmap_domain_gfn_range()
    - xen_free_unpopulated_pages()
    - kvfree(pages)

The surviving VMA still holds the dangling pointer. When it is later
destroyed, the same sequence runs again, which leads to a double free.

Fix this issue by adding a .may_split callback denying the VMA split.

This is XSA-487 / CVE-2026-31787
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Linux ≫ Linux Kernel Version >= 3.8 < 5.10.254
Linux ≫ Linux Kernel Version >= 5.11 < 5.15.204
Linux ≫ Linux Kernel Version >= 5.16 < 6.1.170
Linux ≫ Linux Kernel Version >= 6.2 < 6.6.137
Linux ≫ Linux Kernel Version >= 6.7 < 6.12.85
Linux ≫ Linux Kernel Version >= 6.13 < 6.18.26
Linux ≫ Linux Kernel Version >= 6.19 < 7.0.3
Linux ≫ Linux Kernel Version7.1 Updaterc1
Linux ≫ Linux Kernel Version7.1 Updaterc2
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Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.01% 0.02
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
nvd@nist.gov 7.8 1.8 5.9
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE-415 Double Free

The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations.