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authorSean Christopherson <sean.j.christopherson@intel.com>2020-03-20 13:55:40 -0700
committerPaolo Bonzini <pbonzini@redhat.com>2020-03-26 05:58:27 -0400
commit0774a964ef561b7170d8d1b1bfe6f88002b6d219 (patch)
treee79fd43bb434c3bcd34843d7caee2e65b7f4af25 /arch/s390
parentd5361678e63c8a5e72d75cee6d15b840c44306f2 (diff)
downloadlinux-0774a964ef561b7170d8d1b1bfe6f88002b6d219.tar.bz2
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>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/kvm/kvm-s390.c3
1 files changed, 3 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;