From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Matt Delco <delco@chromium.org>,
Jim Mattson <jmattson@google.com>,
syzbot+983c866c3dd6efa3662a@syzkaller.appspotmail.com,
Paolo Bonzini <pbonzini@redhat.com>
Subject: [PATCH 5.3 11/21] KVM: coalesced_mmio: add bounds checking
Date: Fri, 20 Sep 2019 00:03:12 +0200 [thread overview]
Message-ID: <20190919214706.240209850@linuxfoundation.org> (raw)
In-Reply-To: <20190919214657.842130855@linuxfoundation.org>
From: Matt Delco <delco@chromium.org>
commit b60fe990c6b07ef6d4df67bc0530c7c90a62623a upstream.
The first/last indexes are typically shared with a user app.
The app can change the 'last' index that the kernel uses
to store the next result. This change sanity checks the index
before using it for writing to a potentially arbitrary address.
This fixes CVE-2019-14821.
Cc: stable@vger.kernel.org
Fixes: 5f94c1741bdc ("KVM: Add coalesced MMIO support (common part)")
Signed-off-by: Matt Delco <delco@chromium.org>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reported-by: syzbot+983c866c3dd6efa3662a@syzkaller.appspotmail.com
[Use READ_ONCE. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
virt/kvm/coalesced_mmio.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -40,7 +40,7 @@ static int coalesced_mmio_in_range(struc
return 1;
}
-static int coalesced_mmio_has_room(struct kvm_coalesced_mmio_dev *dev)
+static int coalesced_mmio_has_room(struct kvm_coalesced_mmio_dev *dev, u32 last)
{
struct kvm_coalesced_mmio_ring *ring;
unsigned avail;
@@ -52,7 +52,7 @@ static int coalesced_mmio_has_room(struc
* there is always one unused entry in the buffer
*/
ring = dev->kvm->coalesced_mmio_ring;
- avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
+ avail = (ring->first - last - 1) % KVM_COALESCED_MMIO_MAX;
if (avail == 0) {
/* full */
return 0;
@@ -67,25 +67,28 @@ static int coalesced_mmio_write(struct k
{
struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
+ __u32 insert;
if (!coalesced_mmio_in_range(dev, addr, len))
return -EOPNOTSUPP;
spin_lock(&dev->kvm->ring_lock);
- if (!coalesced_mmio_has_room(dev)) {
+ insert = READ_ONCE(ring->last);
+ if (!coalesced_mmio_has_room(dev, insert) ||
+ insert >= KVM_COALESCED_MMIO_MAX) {
spin_unlock(&dev->kvm->ring_lock);
return -EOPNOTSUPP;
}
/* copy data in first free entry of the ring */
- ring->coalesced_mmio[ring->last].phys_addr = addr;
- ring->coalesced_mmio[ring->last].len = len;
- memcpy(ring->coalesced_mmio[ring->last].data, val, len);
- ring->coalesced_mmio[ring->last].pio = dev->zone.pio;
+ ring->coalesced_mmio[insert].phys_addr = addr;
+ ring->coalesced_mmio[insert].len = len;
+ memcpy(ring->coalesced_mmio[insert].data, val, len);
+ ring->coalesced_mmio[insert].pio = dev->zone.pio;
smp_wmb();
- ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
+ ring->last = (insert + 1) % KVM_COALESCED_MMIO_MAX;
spin_unlock(&dev->kvm->ring_lock);
return 0;
}
next prev parent reply other threads:[~2019-09-19 22:05 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 22:03 [PATCH 5.3 00/21] 5.3.1-stable review Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 01/21] USB: usbcore: Fix slab-out-of-bounds bug during device reset Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 02/21] media: tm6000: double free if usb disconnect while streaming Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 03/21] phy: renesas: rcar-gen3-usb2: Disable clearing VBUS in over-current Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 04/21] ip6_gre: fix a dst leak in ip6erspan_tunnel_xmit Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 05/21] net/sched: fix race between deactivation and dequeue for NOLOCK qdisc Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 06/21] net_sched: let qdisc_put() accept NULL pointer Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 07/21] udp: correct reuseport selection with connected sockets Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 08/21] xen-netfront: do not assume sk_buff_head list is empty in error handling Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 09/21] net: dsa: Fix load order between DSA drivers and taggers Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 10/21] net: stmmac: Hold rtnl lock in suspend/resume callbacks Greg Kroah-Hartman
2019-09-19 22:03 ` Greg Kroah-Hartman [this message]
2019-09-19 22:03 ` [PATCH 5.3 12/21] Documentation: sphinx: Add missing comma to list of strings Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 13/21] firmware: google: check if size is valid when decoding VPD data Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 14/21] serial: sprd: correct the wrong sequence of arguments Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 15/21] tty/serial: atmel: reschedule TX after RX was started Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 16/21] nl80211: Fix possible Spectre-v1 for CQM RSSI thresholds Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 17/21] Revert "arm64: Remove unnecessary ISBs from set_{pte,pmd,pud}" Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 18/21] ovl: fix regression caused by overlapping layers detection Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 19/21] phy: qcom-qmp: Correct ready status, again Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 20/21] floppy: fix usercopy direction Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 5.3 21/21] media: technisat-usb2: break out of loop at end of buffer Greg Kroah-Hartman
2019-09-20 13:45 ` [PATCH 5.3 00/21] 5.3.1-stable review Guenter Roeck
2019-09-20 13:54 ` Jon Hunter
2019-09-20 14:24 ` Greg Kroah-Hartman
2019-09-20 16:01 ` Jon Hunter
2019-09-22 8:13 ` Greg Kroah-Hartman
2019-09-20 14:41 ` Naresh Kamboju
2019-09-21 5:06 ` Greg Kroah-Hartman
2019-09-20 21:17 ` shuah
2019-09-21 5:04 ` Greg Kroah-Hartman
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