Messages in this thread Patch in this message | | | From | Paolo Bonzini <> | Subject | [PATCH] KVM: x86: fix shift out of bounds reported by UBSAN | Date | Tue, 22 Dec 2020 05:21:32 -0500 |
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Since we know that e >= s, we can reassociate the left shift, changing the shifted number from 1 to 2 in exchange for decreasing the right hand side by 1.
Reported-by: syzbot+e87846c48bf72bc85311@syzkaller.appspotmail.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/mmu.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 9c4a9c8e43d9..581925e476d6 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -49,7 +49,7 @@ static inline u64 rsvd_bits(int s, int e) if (e < s) return 0; - return ((1ULL << (e - s + 1)) - 1) << s; + return ((2ULL << (e - s)) - 1) << s; } void kvm_mmu_set_mmio_spte_mask(u64 mmio_value, u64 access_mask); -- 2.26.2
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