[PATCH] net: vmxnet3: validate configuration values during activate (CVE-2021-20203)

From: P J P <ppandit@redhat.com>
To: Dmitry Fleytman <dmitry.fleytman@gmail.com>
Cc: Gaoning Pan <pgn@zju.edu.cn>,
	QEMU Developers <qemu-devel@nongnu.org>,
	Prasad J Pandit <pjp@fedoraproject.org>
Subject: [PATCH] net: vmxnet3: validate configuration values during activate (CVE-2021-20203)
Date: Sat, 30 Jan 2021 18:46:52 +0530	[thread overview]
Message-ID: <20210130131652.954143-1-ppandit@redhat.com> (raw)

From: Prasad J Pandit <pjp@fedoraproject.org>

While activating device in vmxnet3_acticate_device(), it does not
validate guest supplied configuration values against predefined
minimum - maximum limits. This may lead to integer overflow or
OOB access issues. Add checks to avoid it.

Fixes: CVE-2021-20203
Buglink: https://bugs.launchpad.net/qemu/+bug/1913873
Reported-by: Gaoning Pan <pgn@zju.edu.cn>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 hw/net/vmxnet3.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
index eff299f629..4a910ca971 100644
--- a/hw/net/vmxnet3.c
+++ b/hw/net/vmxnet3.c
@@ -1420,6 +1420,7 @@ static void vmxnet3_activate_device(VMXNET3State *s)
     vmxnet3_setup_rx_filtering(s);
     /* Cache fields from shared memory */
     s->mtu = VMXNET3_READ_DRV_SHARED32(d, s->drv_shmem, devRead.misc.mtu);
+    assert(VMXNET3_MIN_MTU <= s->mtu && s->mtu < VMXNET3_MAX_MTU);
     VMW_CFPRN("MTU is %u", s->mtu);
 
     s->max_rx_frags =
@@ -1473,6 +1474,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
         /* Read rings memory locations for TX queues */
         pa = VMXNET3_READ_TX_QUEUE_DESCR64(d, qdescr_pa, conf.txRingBasePA);
         size = VMXNET3_READ_TX_QUEUE_DESCR32(d, qdescr_pa, conf.txRingSize);
+        if (size > VMXNET3_TX_RING_MAX_SIZE) {
+            size = VMXNET3_TX_RING_MAX_SIZE;
+        }
 
         vmxnet3_ring_init(d, &s->txq_descr[i].tx_ring, pa, size,
                           sizeof(struct Vmxnet3_TxDesc), false);
@@ -1483,6 +1487,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
         /* TXC ring */
         pa = VMXNET3_READ_TX_QUEUE_DESCR64(d, qdescr_pa, conf.compRingBasePA);
         size = VMXNET3_READ_TX_QUEUE_DESCR32(d, qdescr_pa, conf.compRingSize);
+        if (size > VMXNET3_TC_RING_MAX_SIZE) {
+            size = VMXNET3_TC_RING_MAX_SIZE;
+        }
         vmxnet3_ring_init(d, &s->txq_descr[i].comp_ring, pa, size,
                           sizeof(struct Vmxnet3_TxCompDesc), true);
         VMXNET3_RING_DUMP(VMW_CFPRN, "TXC", i, &s->txq_descr[i].comp_ring);
@@ -1524,6 +1531,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
             /* RX rings */
             pa = VMXNET3_READ_RX_QUEUE_DESCR64(d, qd_pa, conf.rxRingBasePA[j]);
             size = VMXNET3_READ_RX_QUEUE_DESCR32(d, qd_pa, conf.rxRingSize[j]);
+            if (size > VMXNET3_RX_RING_MAX_SIZE) {
+                size = VMXNET3_RX_RING_MAX_SIZE;
+            }
             vmxnet3_ring_init(d, &s->rxq_descr[i].rx_ring[j], pa, size,
                               sizeof(struct Vmxnet3_RxDesc), false);
             VMW_CFPRN("RX queue %d:%d: Base: %" PRIx64 ", Size: %d",
@@ -1533,6 +1543,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
         /* RXC ring */
         pa = VMXNET3_READ_RX_QUEUE_DESCR64(d, qd_pa, conf.compRingBasePA);
         size = VMXNET3_READ_RX_QUEUE_DESCR32(d, qd_pa, conf.compRingSize);
+        if (size > VMXNET3_RC_RING_MAX_SIZE) {
+            size = VMXNET3_RC_RING_MAX_SIZE;
+        }
         vmxnet3_ring_init(d, &s->rxq_descr[i].comp_ring, pa, size,
                           sizeof(struct Vmxnet3_RxCompDesc), true);
         VMW_CFPRN("RXC queue %d: Base: %" PRIx64 ", Size: %d", i, pa, size);
-- 
2.29.2


