Description
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping While VNCR TLB invalidation always occurs under the MMU lock, vcpu_put() doesn't, while it unmaps the VNCR page. The problem is that the invalidation evaluates vncr_tlb::cpu to decide whether an unmapping needs to take place (cpu != -1) before performing it. On the other hand, this_cpu_reset_vncr_fixmap() unconditionally unmaps if L1_VNCR_MAPPED is set. These two obviously can race, with a TOCTOU pattern on the TLBI path, and a BUG_ON() on the vcpu_put() path. And the two can end-up calling vncr_fixmap(-1), with extra lethal effects. Move the reset of vncr_tlb::cpu to -1 to a common function, and make this update atomic so that only a single thread can reset the field and perform the corresponding unmap. The vcpu_put() still need to unconditionally unmap the current VNCR to close another ugly race. Finally, the assignment of vncr_tlb::cpu is moved to be kept in sync with the actual mapping, similar to L1_VNCR_MAPPED being set.
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
7270cc9157f474dfc46750a34c9d7defc686b2eb to < 5cbd8761d001c11ada73b1753d772c4745a70e72affected7270cc9157f474dfc46750a34c9d7defc686b2eb to < 9065c1261f8a05c6a7a2d90048c7c0665ab2896daffected7270cc9157f474dfc46750a34c9d7defc686b2eb to < 38640bc32be3fcf9526d477155bc19d3f146231faffected
Linux Linux
Default version status: affected
6.16affected0 to < 6.16unaffected6.18.52 to ≤ 6.18.*unaffected7.2.5 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected