Description: Linux: KVM VM_IO|VM_PFNMAP vma mishandling
References:
 https://github.com/google/security-research/security/advisories/GHSA-7wq5-phmq-m584
 https://www.openwall.com/lists/oss-security/2021/05/26/3
Notes:
 bwh> For 4.9, at least commits bd2fae8da794 "KVM: do not assume PTE is
 bwh> writable after follow_pfn" and 097963959594 "mm: add follow_pte_pmd()"
 bwh> need to be applied first.
Bugs:
upstream: released (5.13) [f8be156be163a052a067306417cd0ff679068c97]
5.10-upstream-stable: released (5.10.47) [dd8ed6c9bc2224c1ace5292d01089d3feb7ebbc3]
4.19-upstream-stable: released (4.19.199) [117777467bc015f0dc5fc079eeba0fa80c965149]
4.9-upstream-stable: released (4.9.298) [f4b2bfed80e8d0e91b431dd1c21bc3c2c4d5f07e]
sid: released (5.10.46-2) [bugfix/all/KVM-do-not-allow-mapping-valid-but-non-reference-cou.patch]
5.10-bullseye-security: N/A "Fixed before branching point"
4.19-buster-security: released (4.19.208-1)
4.9-stretch-security: released (4.9.290-1) [bugfix/all/kvm-do-not-allow-mapping-valid-but-non-reference-cou.patch]