From: Eric Biggers <ebiggers@kernel.org>
To: kvm@vger.kernel.org, "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>
Cc: Peng Hao <peng.hao2@zte.com.cn>,
syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org
Subject: [PATCH] KVM: fix unregistering coalesced mmio zone from wrong bus
Date: Mon, 17 Dec 2018 09:36:19 -0800 [thread overview]
Message-ID: <20181217173619.210795-1-ebiggers@kernel.org> (raw)
In-Reply-To: <5b22a63b-e4c2-58af-8070-5aec20302dfc@redhat.com>
From: Eric Biggers <ebiggers@google.com>
If you register a kvm_coalesced_mmio_zone with '.pio = 0' but then
unregister it with '.pio = 1', KVM_UNREGISTER_COALESCED_MMIO will try to
unregister it from KVM_PIO_BUS rather than KVM_MMIO_BUS, which is a
no-op. But it frees the kvm_coalesced_mmio_dev anyway, causing a
use-after-free.
Fix it by only unregistering and freeing the zone if the correct value
of 'pio' is provided.
Reported-by: syzbot+f87f60bb6f13f39b54e3@syzkaller.appspotmail.com
Fixes: 0804c849f1df ("kvm/x86 : add coalesced pio support")
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
virt/kvm/coalesced_mmio.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index 3710342cf6ad0..6855cce3e5287 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -175,10 +175,14 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
{
struct kvm_coalesced_mmio_dev *dev, *tmp;
+ if (zone->pio != 1 && zone->pio != 0)
+ return -EINVAL;
+
mutex_lock(&kvm->slots_lock);
list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list)
- if (coalesced_mmio_in_range(dev, zone->addr, zone->size)) {
+ if (zone->pio == dev->zone.pio &&
+ coalesced_mmio_in_range(dev, zone->addr, zone->size)) {
kvm_io_bus_unregister_dev(kvm,
zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev);
kvm_iodevice_destructor(&dev->dev);
--
2.20.0.405.gbc1bbc6f85-goog
next prev parent reply other threads:[~2018-12-17 17:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-20 16:57 KASAN: use-after-free Read in kvm_put_kvm syzbot
2018-10-21 10:01 ` Paolo Bonzini
2018-12-16 18:55 ` KASAN: use-after-free Read in kvm_put_kvm (caused by: "kvm/x86: add coalesced pio support") Eric Biggers
2018-12-17 15:58 ` Paolo Bonzini
2018-12-17 17:36 ` Eric Biggers [this message]
2018-12-18 21:03 ` Paolo Bonzini
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