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KVM: x86: fix shift out of bounds reported by UBSAN

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commit 2f80d502d627f30257ba7e3655e71c373b7d1a5a upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Paolo Bonzini 2020-12-22 05:20:43 -05:00 committed by Greg Kroah-Hartman
parent 4dd18f7893
commit 1412cdde82
1 changed files with 1 additions and 1 deletions
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arch/x86/kvm/mmu.h
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@ -53,7 +53,7 @@ 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_mask, u64 mmio_value);