KVM: PPC: Book3S HV: fix use-after-free in kvmhv_emulate_tlbie_all_lpid()
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.1.189, 6.6.158, 6.12.112, 6.18.54, 7.2.8
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: PPC: Book3S HV: fix use-after-free in kvmhv_emulate_tlbie_all_lpid() kvmhv_emulate_tlbie_all_lpid() iterates the nested-guest IDR and drops mmu_lock before calling kvmhv_emulate_tlbie_lpid(), but does not hold a reference on the kvm_nested_guest pointer obtained from the IDR. A concurrent vCPU issuing a single-LPID tlbie (is=2, ric=2) can race through kvmhv_flush_nested() -> kvmhv_remove_nested() -> idr_remove / --refcnt -> kvmhv_release_nested() -> kfree(gp) in that window, leaving the iterating vCPU with a dangling pointer. The subsequent mutex_lock(&gp->tlb_lock) and accesses to gp->shadow_pgtable, gp->shadow_lpid and gp->l1_host all touch freed memory. The free path is fully L1-controlled. Fix this by incrementing gp->refcnt inside the loop before dropping mmu_lock, mirroring what kvmhv_get_nested() does, and releasing the reference with kvmhv_put_nested() after the per-guest work completes. This is the same get/put discipline already used at every other call site that drops mmu_lock while holding a nested-guest pointer.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From e3b6b4661527e821ffbe3db83952fdb1e6e47c49 · fixed in 4d8f7b1f586375df8bce23a0909566ad5e852259; From e3b6b4661527e821ffbe3db83952fdb1e6e47c49 · fixed in e37fba1ba69385cff2d0e60b371ee19e7d1852d1; From e3b6b4661527e821ffbe3db83952fdb1e6e47c49 · fixed in 24b634852413229bb8340d908b115c3365f3a247; From e3b6b4661527e821ffbe3db83952fdb1e6e47c49 · fixed in fbf69b7d0555ee83c871f58750770f74b7179ad1; From e3b6b4661527e821ffbe3db83952fdb1e6e47c49 · fixed in ec2d7a52b3996ae81131617b4afc0af31583c1b4; From e3b6b4661527e821ffbe3db83952fdb1e6e47c49 · fixed in 51938dfa8a51a4f85328413fca9b6e21f9d2d088
- Linux Linux
4.20
- KernelLinux
From 4.20.0 · fixed in 6.1.189; From 6.2.0 · fixed in 6.6.158; From 6.7.0 · fixed in 6.12.112; From 6.13.0 · fixed in 6.18.54; From 6.19.0 · fixed in 7.2.8