From 0774a964ef561b7170d8d1b1bfe6f88002b6d219 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 20 Mar 2020 13:55:40 -0700 Subject: 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 Cc: Peter Xu Signed-off-by: Sean Christopherson Message-Id: <20200320205546.2396-2-sean.j.christopherson@intel.com> Acked-by: Christian Borntraeger Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/kvm_host.h') 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]; -- cgit