[pve-devel] [PATCH pve-qemu] patch for possible DOS in qemu network packet processing

[Oguz Bektas <o.bektas@proxmox.com>]

fixes an assertion failure in qemu network packet processing, which can
lead to DOS'ing the qemu process on the host. this affects 'e1000e' and
'vmxnet3' network devices.

patch is cherry-picked from the commit mentioned in the oss-security email.

more info on oss-security [0]

[0]: https://www.openwall.com/lists/oss-security/2020/08/10/1

Signed-off-by: Oguz Bektas <o.bektas@proxmox.com>
---
 ...t-fix-assertion-failure-in-net_tx_pk.patch | 42 +++++++++++++++++++
 debian/patches/series                         |  1 +
 2 files changed, 43 insertions(+)
 create mode 100644 debian/patches/extra/0002-hw-net-net_tx_pkt-fix-assertion-failure-in-net_tx_pk.patch

diff --git a/debian/patches/extra/0002-hw-net-net_tx_pkt-fix-assertion-failure-in-net_tx_pk.patch b/debian/patches/extra/0002-hw-net-net_tx_pkt-fix-assertion-failure-in-net_tx_pk.patch
new file mode 100644
index 0000000..1b4b2c4
--- /dev/null
+++ b/debian/patches/extra/0002-hw-net-net_tx_pkt-fix-assertion-failure-in-net_tx_pk.patch
@@ -0,0 +1,42 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Mauro Matteo Cascella <mcascell@redhat.com>
+Date: Sat, 1 Aug 2020 18:42:38 +0200
+Subject: [PATCH] hw/net/net_tx_pkt: fix assertion failure in
+ net_tx_pkt_add_raw_fragment()
+
+An assertion failure issue was found in the code that processes network packets
+while adding data fragments into the packet context. It could be abused by a
+malicious guest to abort the QEMU process on the host. This patch replaces the
+affected assert() with a conditional statement, returning false if the current
+data fragment exceeds max_raw_frags.
+
+Reported-by: Alexander Bulekov <alxndr@bu.edu>
+Reported-by: Ziming Zhang <ezrakiez@gmail.com>
+Reviewed-by: Dmitry Fleytman <dmitry.fleytman@gmail.com>
+Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
+Signed-off-by: Jason Wang <jasowang@redhat.com>
+(cherry picked from commit 035e69b063835a5fd23cacabd63690a3d84532a8)
+Signed-off-by: Oguz Bektas <o.bektas@proxmox.com>
+---
+ hw/net/net_tx_pkt.c | 5 ++++-
+ 1 file changed, 4 insertions(+), 1 deletion(-)
+
+diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
+index 162f802dd7..54d4c3bbd0 100644
+--- a/hw/net/net_tx_pkt.c
++++ b/hw/net/net_tx_pkt.c
+@@ -379,7 +379,10 @@ bool net_tx_pkt_add_raw_fragment(struct NetTxPkt *pkt, hwaddr pa,
+     hwaddr mapped_len = 0;
+     struct iovec *ventry;
+     assert(pkt);
+-    assert(pkt->max_raw_frags > pkt->raw_frags);
++
++    if (pkt->raw_frags >= pkt->max_raw_frags) {
++        return false;
++    }
+ 
+     if (!len) {
+         return true;
+-- 
+2.20.1
+
diff --git a/debian/patches/series b/debian/patches/series
index 00d2c7d..531c5b9 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -1,4 +1,5 @@
 extra/0001-hw-vfio-pci-quirks-Fix-broken-legacy-IGD-passthrough.patch
+extra/0002-hw-net-net_tx_pkt-fix-assertion-failure-in-net_tx_pk.patch
 pve/0001-PVE-Config-block-file-change-locking-default-to-off.patch
 pve/0002-PVE-Config-Adjust-network-script-path-to-etc-kvm.patch
 pve/0003-PVE-Config-set-the-CPU-model-to-kvm64-32-instead-of-.patch
-- 
2.20.1