In the Linux kernel, the following vulnerability has been resolved:
virtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false
A UAF issue occurs when the virtio_net driver is configured with napi_tx=N
and the device's IFF_XMIT_DST_RELEASE flag is cleared
(e.g., during the configuration of tc route filter rules).
When IFF_XMIT_DST_RELEASE is removed from the net_device, the network stack
expects the driver to hold the reference to skb->dst until the packet
is fully transmitted and freed. In virtio_net with napi_tx=N,
skbs may remain in the virtio transmit ring for an extended period.
If the network namespace is destroyed while these skbs are still pending,
the corresponding dst_ops structure has freed. When a subsequent packet
is transmitted, free_old_xmit() is triggered to clean up old skbs.
It then calls dst_release() on the skb associated with the stale dst_entry.
Since the dst_ops (referenced by the dst_entry) has already been freed,
a UAF kernel paging request occurs.
fix it by adds skb_dst_drop(skb) in start_xmit to explicitly release
the dst reference before the skb is queued in virtio_net.
Call Trace:
Unable to handle kernel paging request at virtual address ffff80007e150000
CPU: 2 UID: 0 PID: 6236 Comm: ping Kdump: loaded Not tainted 7.0.0-rc1+ #6 PREEMPT
...
percpu_counter_add_batch+0x3c/0x158 lib/percpu_counter.c:98 (P)
dst_release+0xe0/0x110 net/core/dst.c:177
skb_release_head_state+0xe8/0x108 net/core/skbuff.c:1177
sk_skb_reason_drop+0x54/0x2d8 net/core/skbuff.c:1255
dev_kfree_skb_any_reason+0x64/0x78 net/core/dev.c:3469
napi_consume_skb+0x1c4/0x3a0 net/core/skbuff.c:1527
__free_old_xmit+0x164/0x230 drivers/net/virtio_net.c:611 [virtio_net]
free_old_xmit drivers/net/virtio_net.c:1081 [virtio_net]
start_xmit+0x7c/0x530 drivers/net/virtio_net.c:3329 [virtio_net]
...
Reproduction Steps:
NETDEV="enp3s0"
config_qdisc_route_filter() {
tc qdisc del dev $NETDEV root
tc qdisc add dev $NETDEV root handle 1: prio
tc filter add dev $NETDEV parent 1:0 \
protocol ip prio 100 route to 100 flowid 1:1
ip route add 192.168.1.100/32 dev $NETDEV realm 100
}
test_ns() {
ip netns add testns
ip link set $NETDEV netns testns
ip netns exec testns ifconfig $NETDEV 10.0.32.46/24
ip netns exec testns ping -c 1 10.0.32.1
ip netns del testns
}
config_qdisc_route_filter
test_ns
sleep 2
test_ns
References
Configurations
Configuration 1 (hide)
|
History
07 May 2026, 18:18
| Type | Values Removed | Values Added |
|---|---|---|
| CWE | CWE-416 | |
| CPE | cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* |
|
| References | () https://git.kernel.org/stable/c/63d45077b97bb0e0fe0c75931acbbca7a47af141 - Patch | |
| References | () https://git.kernel.org/stable/c/8a4790850e710fd6771e4d2112168ed1dd6c0e54 - Patch | |
| References | () https://git.kernel.org/stable/c/9a18629f2525781f0f3dda7be72b204e4cf77d08 - Patch | |
| References | () https://git.kernel.org/stable/c/ba8bda9a0896746053aa97ac6c3e08168729172c - Patch | |
| References | () https://git.kernel.org/stable/c/be0e63f3b97bbaf453c542e8a15ba2a536e2ac01 - Patch | |
| References | () https://git.kernel.org/stable/c/c1ec36cb3768574b916f20d2d7415fd14fa1bf12 - Patch | |
| References | () https://git.kernel.org/stable/c/f04733c4dc40c43899c3d1c97afbae5831a3770f - Patch | |
| References | () https://git.kernel.org/stable/c/fedd2e1630cac920844997227ccbe7b26a76375a - Patch | |
| First Time |
Linux linux Kernel
Linux |
27 Apr 2026, 14:16
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.8 |
22 Apr 2026, 14:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-04-22 14:16
Updated : 2026-05-07 18:18
NVD link : CVE-2026-31469
Mitre link : CVE-2026-31469
CVE.ORG link : CVE-2026-31469
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-416
Use After Free