diff options
| author | Sean Christopherson <sean.j.christopherson@intel.com> | 2020-03-20 13:55:40 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-03-26 05:58:27 -0400 |
| commit | 0774a964ef561b7170d8d1b1bfe6f88002b6d219 (patch) | |
| tree | e79fd43bb434c3bcd34843d7caee2e65b7f4af25 | |
| parent | d5361678e63c8a5e72d75cee6d15b840c44306f2 (diff) | |
KVM: Fix out of range accesses to memslots
Reset the LRU slot if it becomes invalid when deleting a memslot to fix
an out-of-bounds/use-after-free access when searching through memslots.
Explicitly check for there being no used slots in search_memslots(), and
in the caller of s390's approximation variant.
Fixes: 36947254e5f9 ("KVM: Dynamically size memslot array based on number of used slots")
Reported-by: Qian Cai <cai@lca.pw>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200320205546.2396-2-sean.j.christopherson@intel.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/s390/kvm/kvm-s390.c | 3 | ||||
| -rw-r--r-- | include/linux/kvm_host.h | 3 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 3 |
3 files changed, 9 insertions, 0 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 807ed6d722dd..cb15fdda1fee 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -2002,6 +2002,9 @@ static int kvm_s390_get_cmma(struct kvm *kvm, struct kvm_s390_cmma_log *args, struct kvm_memslots *slots = kvm_memslots(kvm); struct kvm_memory_slot *ms; + if (unlikely(!slots->used_slots)) + return 0; + cur_gfn = kvm_s390_next_dirty_cmma(slots, args->start_gfn); ms = gfn_to_memslot(kvm, cur_gfn); args->count = 0; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 35bc52e187a2..b19dee4ed7d9 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1032,6 +1032,9 @@ search_memslots(struct kvm_memslots *slots, gfn_t gfn) int slot = atomic_read(&slots->lru_slot); struct kvm_memory_slot *memslots = slots->memslots; + if (unlikely(!slots->used_slots)) + return NULL; + if (gfn >= memslots[slot].base_gfn && gfn < memslots[slot].base_gfn + memslots[slot].npages) return &memslots[slot]; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 28eae681859f..f744bc603c53 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -882,6 +882,9 @@ static inline void kvm_memslot_delete(struct kvm_memslots *slots, slots->used_slots--; + if (atomic_read(&slots->lru_slot) >= slots->used_slots) + atomic_set(&slots->lru_slot, 0); + for (i = slots->id_to_index[memslot->id]; i < slots->used_slots; i++) { mslots[i] = mslots[i + 1]; slots->id_to_index[mslots[i].id] = i; |