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From: Paolo Bonzini <pbonzini@redhat.com>
To: Sasha Levin <sasha.levin@oracle.com>, Gleb Natapov <gleb@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Dmitry Vyukov <dvyukov@google.com>,
	syzkaller <syzkaller@googlegroups.com>
Subject: Re: kvm: using uninitialized var in tdp_page_fault
Date: Tue, 23 Feb 2016 15:30:54 +0100	[thread overview]
Message-ID: <56CC6D1E.5070503@redhat.com> (raw)
In-Reply-To: <56992619.5030009@oracle.com>



On 15/01/2016 18:02, Sasha Levin wrote:
> Hi all,
> 
> While fuzzing with syzkaller on the latest -next kernel running on a KVM tools
> guest, I've hit the following use of an uninitialized variable:
> 
> [  810.783676] UBSAN: Undefined behaviour in arch/x86/kvm/mmu.c:3502:6
> 
> [  810.785650] load of value 179 is not a valid value for type '_Bool'

Can you check this patch:

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index be3cef12706c..fd54613a1204 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1449,8 +1449,11 @@ pfn_t __gfn_to_pfn_memslot(struct
 	if (addr == KVM_HVA_ERR_RO_BAD)
 		return KVM_PFN_ERR_RO_FAULT;
 
-	if (kvm_is_error_hva(addr))
+	if (kvm_is_error_hva(addr)) {
+		if (writable)
+			*writable = false;
 		return KVM_PFN_NOSLOT;
+	}
 
 	/* Do not map writable pfn in the readonly memslot. */
 	if (writable && memslot_is_readonly(slot)) {

Thanks,

Paolo

  reply	other threads:[~2016-02-23 14:30 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-15 17:02 kvm: using uninitialized var in tdp_page_fault Sasha Levin
2016-02-23 14:30 ` Paolo Bonzini [this message]
2016-02-28 13:08   ` Dmitry Vyukov

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