From a2ac07fe292ea41296049dfdbfeed203e2467ee7 Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Tue, 1 Oct 2013 19:58:36 +0300 Subject: Fix NULL dereference in gfn_to_hva_prot() gfn_to_memslot() can return NULL or invalid slot. We need to check slot validity before accessing it. Reviewed-by: Paolo Bonzini Signed-off-by: Gleb Natapov --- virt/kvm/kvm_main.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 979bff485fb0..a9dd682cf5e3 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1064,10 +1064,12 @@ EXPORT_SYMBOL_GPL(gfn_to_hva); unsigned long gfn_to_hva_prot(struct kvm *kvm, gfn_t gfn, bool *writable) { struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn); - if (writable) + unsigned long hva = __gfn_to_hva_many(slot, gfn, NULL, false); + + if (!kvm_is_error_hva(hva) && writable) *writable = !memslot_is_readonly(slot); - return __gfn_to_hva_many(gfn_to_memslot(kvm, gfn), gfn, NULL, false); + return hva; } static int kvm_read_hva(void *data, void __user *hva, int len) -- cgit v1.2.3