Description
In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Check for invalid/obsolete root *after* making MMU pages available Check for a "stale" page fault, i.e. for an invalid and/or obsolete root, after making MMU pages available for the shadow MMU. If reclaiming shadow pages zaps an in-use root, i.e. marks it invalid, then KVM will attempt to map memory into an invalid root. On its own, populating an invalid root is "fine", but because child shadow pages inherit their parent's role, any children created during the map/fetch will be created as invalid pages, thus violating KVM's invariant that invalid pages are never on the list of active MMU pages. Note, the underlying flaw has existed since KVM first started tracking invalid roots in 2008 (commit 2e53d63acba7, "KVM: MMU: ignore zapped root pagetables"), but the true badness only came along in 2020 (Linux 5.9) with the invariant that invalid shadow pages can't be on the list of active pages. Note #2, inheriting role.invalid when creating child shadow pages is also far from ideal; that flaw will be addressed separately.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
f95eec9bed76d42194c23153cb1cc8f186bf91cb to < 62ef67af1878fa2cd066642f2f59e33ade95f637affectedf95eec9bed76d42194c23153cb1cc8f186bf91cb to < 65c4f7a1028cf01a93a2762d679c289810ede990affectedf95eec9bed76d42194c23153cb1cc8f186bf91cb to < 35e77467610c4a37cb0ff54ee56b85f73b1f5700affectedf95eec9bed76d42194c23153cb1cc8f186bf91cb to < 0026dbb7de8ea76e97d6edf42fc3cc084564e2bfaffectedf95eec9bed76d42194c23153cb1cc8f186bf91cb to < f3477a6a4164f15287444eda685b5f6405dbd1e5affectedf95eec9bed76d42194c23153cb1cc8f186bf91cb to < bce0d3c26e2c761a4bf43c8949f333fc7374eb2daffectedf95eec9bed76d42194c23153cb1cc8f186bf91cb to < 2abd5287f08319fa35764566b15c6e22cb1068dbaffected
Linux Linux
Default version status: affected
5.9affected0 to < 5.9unaffected5.15.218 to ≤ 5.15.*unaffected6.1.183 to ≤ 6.1.*unaffected6.6.148 to ≤ 6.6.*unaffected6.12.101 to ≤ 6.12.*unaffected6.18.42 to ≤ 6.18.*unaffected7.1.6 to ≤ 7.1.*unaffected7.2 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/62ef67af1878fa2cd066642f2f59e33ade95f637 ↗
- https://git.kernel.org/stable/c/65c4f7a1028cf01a93a2762d679c289810ede990 ↗
- https://git.kernel.org/stable/c/35e77467610c4a37cb0ff54ee56b85f73b1f5700 ↗
- https://git.kernel.org/stable/c/0026dbb7de8ea76e97d6edf42fc3cc084564e2bf ↗
- https://git.kernel.org/stable/c/f3477a6a4164f15287444eda685b5f6405dbd1e5 ↗
- https://git.kernel.org/stable/c/bce0d3c26e2c761a4bf43c8949f333fc7374eb2d ↗
- https://git.kernel.org/stable/c/2abd5287f08319fa35764566b15c6e22cb1068db ↗
- https://github.com/V4bel/Zapscape ↗