linux-kernel - [PATCH 1/2] KVM: arm64: Fix off-by-one in range_is

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Message-Id: <20210728153232.1018911-2-dbrazdil@google.com>
Date:   Wed, 28 Jul 2021 15:32:31 +0000
From:   David Brazdil <dbrazdil@...gle.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Quentin Perret <qperret@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        David Brazdil <dbrazdil@...gle.com>
Subject: [PATCH 1/2] KVM: arm64: Fix off-by-one in range_is_memory

Hyp checks whether an address range only covers RAM by checking the
start/endpoints against a list of memblock_region structs. However,
the endpoint here is exclusive but internally is treated as inclusive.
Fix the off-by-one error that caused valid address ranges to be
rejected.

Cc: Quentin Perret <qperret@...gle.com>
Fixes: 90134ac9cabb6 ("KVM: arm64: Protect the .hyp sections from the host")
Signed-off-by: David Brazdil <dbrazdil@...gle.com>
---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index d938ce95d3bd..a6ce991b1467 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -193,7 +193,7 @@ static bool range_is_memory(u64 start, u64 end)
 {
 	struct kvm_mem_range r1, r2;
 
-	if (!find_mem_range(start, &r1) || !find_mem_range(end, &r2))
+	if (!find_mem_range(start, &r1) || !find_mem_range(end - 1, &r2))
 		return false;
 	if (r1.start != r2.start)
 		return false;
-- 
2.32.0.432.gabb21c7263-goog