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CVE-2026-68166

userfaultfd: prevent registration of special VMAs PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: userfaultfd: prevent registration of special VMAs Vova Tokarev says: userfaultfd allows registration on shadow stack VMAs. With userfaultfd access, you can register on the shadow stack, discard a page ... and inject a page with chosen return addresses via UFFDIO_COPY. Update vma_can_userfault() to reject VM_SHADOW_STACK. While on it, also reject VM_SPECIAL so that if a driver would implement vm_uffd_ops, it wouldn't be possible to register special VMAs with userfaultfd. Since VM_SPECIAL includes VM_DONTEXPAND which is set but hugetlb, exclude hugetlb VMAs from the check for VM_SPECIAL.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 54007f818206dc27309ca423df4c87dd160a7208 before d974b4b786214883bd8e56bda10b454c80fd6205; affected 54007f818206dc27309ca423df4c87dd160a7208 before 495a28d5a100be1b232633f4c2dcc42ba10b3796; affected 54007f818206dc27309ca423df4c87dd160a7208 before 165613191ad9d034bf17c00e3a142f9561597ec5; affected 54007f818206dc27309ca423df4c87dd160a7208 before 0c26202b157f1efc3cd2f26f5c30f59b508a6a5d; affected 54007f818206dc27309ca423df4c87dd160a7208 before 3c58f641e813c3c71039f8fd4d4e2a3aab713288
Linux / Linuxaffected 6.6; unaffected 0 before 6.6; unaffected 6.6.153 through 6.6.*; unaffected 6.12.105 through 6.12.*; unaffected 6.18.44 through 6.18.*; unaffected 7.1.6 through 7.1.*; unaffected 7.2 through *

CWE

No CWE identifiers supplied.

References