From: Zenghui Yu <yuzenghui@huawei.com>
To: <maz@kernel.org>, <kvmarm@lists.cs.columbia.edu>,
<linux-arm-kernel@lists.infradead.org>
Cc: suzuki.poulose@arm.com, marc.zyngier@arm.com,
julien.thierry@arm.com, linux-kernel@vger.kernel.org,
james.morse@arm.com, andrew.murray@arm.com,
Zenghui Yu <yuzenghui@huawei.com>,
wanghaibin.wang@huawei.com, julien.thierry.kdev@gmail.com
Subject: [PATCH] KVM: arm/arm64: Assign pmc->idx before kvm_pmu_stop_counter()
Date: Wed, 17 Jul 2019 12:20:19 +0000 [thread overview]
Message-ID: <1563366019-31200-1-git-send-email-yuzenghui@huawei.com> (raw)
We use "pmc->idx" and the "chained" bitmap to determine if the pmc is
chained, in kvm_pmu_pmc_is_chained(). But idx might be uninitialized
(and random) when we doing this decision, through a KVM_ARM_VCPU_INIT
ioctl -> kvm_pmu_vcpu_reset(). And the test_bit() against this random
idx will potentially hit a KASAN BUG [1].
Fix it by moving the assignment of idx before kvm_pmu_stop_counter().
[1] https://www.spinics.net/lists/kvm-arm/msg36700.html
Fixes: 80f393a23be6 ("KVM: arm/arm64: Support chained PMU counters")
Suggested-by: Andrew Murray <andrew.murray@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
---
virt/kvm/arm/pmu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index 3dd8238..521bfdd 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -225,8 +225,8 @@ void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu)
struct kvm_pmu *pmu = &vcpu->arch.pmu;
for (i = 0; i < ARMV8_PMU_MAX_COUNTERS; i++) {
- kvm_pmu_stop_counter(vcpu, &pmu->pmc[i]);
pmu->pmc[i].idx = i;
+ kvm_pmu_stop_counter(vcpu, &pmu->pmc[i]);
}
bitmap_zero(vcpu->arch.pmu.chained, ARMV8_PMU_MAX_COUNTER_PAIRS);
--
1.8.3.1
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next reply other threads:[~2019-07-17 12:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-17 12:20 Zenghui Yu [this message]
2019-07-17 13:44 ` [PATCH] KVM: arm/arm64: Assign pmc->idx before kvm_pmu_stop_counter() Julien Thierry
2019-07-17 15:00 ` Marc Zyngier
2019-07-18 1:59 ` Zenghui Yu
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