Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1602751 > unrolled thread

[PATCH v2 0/3] kvm: arm/arm64: Fixes for use after free problems

Back to article view | Back to linux.kernel

Contents

  [PATCH v2 0/3] kvm: arm/arm64: Fixes for use after free problems Suzuki K Poulose <suzuki.poulose@arm.com> - 2017-03-16 19:30 +0100
    [PATCH v2 2/3] kvm: arm/arm64: Take mmap_sem in kvm_arch_prepare_memory_region Suzuki K Poulose <suzuki.poulose@arm.com> - 2017-03-16 19:30 +0100

#1602751 — [PATCH v2 0/3] kvm: arm/arm64: Fixes for use after free problems

This series contains potential fixes for problems reported by [0] & [1].

[0] http://lists.infradead.org/pipermail/linux-arm-kernel/2017-March/492944.html
[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2017-March/492943.html

Changes since V1:
 - Yield the kvm->mmu_lock if necessary in unmap_stage2_range to prevent
   vCPU starvation and lockup detector warnings.

Marc Zyngier (2):
  kvm: arm/arm64: Take mmap_sem in stage2_unmap_vm
  kvm: arm/arm64: Take mmap_sem in kvm_arch_prepare_memory_region

Suzuki K Poulose (1):
  kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd

 arch/arm/kvm/mmu.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

-- 
2.7.4

[toc] | [next] | [standalone]

#1602754 — [PATCH v2 2/3] kvm: arm/arm64: Take mmap_sem in kvm_arch_prepare_memory_region

From: Marc Zyngier <marc.zyngier@arm.com>

We don't hold the mmap_sem while searching for VMAs (via find_vma), in
kvm_arch_prepare_memory_region, which can end up in expected failures.

Fixes: commit 8eef91239e57 ("arm/arm64: KVM: map MMIO regions at creation time")
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Eric Auger <eric.auger@rehat.com>
Cc: stable@vger.kernel.org # v3.18+
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
[ Handle dirty page logging failure case ]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 arch/arm/kvm/mmu.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index f2e2e0c..13b9c1f 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -1803,6 +1803,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	    (KVM_PHYS_SIZE >> PAGE_SHIFT))
 		return -EFAULT;
 
+	down_read(&current->mm->mmap_sem);
 	/*
 	 * A memory region could potentially cover multiple VMAs, and any holes
 	 * between them, so iterate over all of them to find out if we can map
@@ -1846,8 +1847,10 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 			pa += vm_start - vma->vm_start;
 
 			/* IO region dirty page logging not allowed */
-			if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES)
-				return -EINVAL;
+			if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES) {
+				ret = -EINVAL;
+				goto out;
+			}
 
 			ret = kvm_phys_addr_ioremap(kvm, gpa, pa,
 						    vm_end - vm_start,
@@ -1859,7 +1862,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	} while (hva < reg_end);
 
 	if (change == KVM_MR_FLAGS_ONLY)
-		return ret;
+		goto out;
 
 	spin_lock(&kvm->mmu_lock);
 	if (ret)
@@ -1867,6 +1870,8 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	else
 		stage2_flush_memslot(kvm, memslot);
 	spin_unlock(&kvm->mmu_lock);
+out:
+	up_read(&current->mm->mmap_sem);
 	return ret;
 }
 
-- 
2.7.4

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web