virtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false

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Summary

CVECVE-2026-31469
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-22 14:16:43 UTC
Updated2026-04-22 14:16:43 UTC
DescriptionIn 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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected f2fc6a54585a1be6669613a31fbaba2ecbadcd36 be0e63f3b97bbaf453c542e8a15ba2a536e2ac01 git Not specified
CNA Linux Linux affected f2fc6a54585a1be6669613a31fbaba2ecbadcd36 c1ec36cb3768574b916f20d2d7415fd14fa1bf12 git Not specified
CNA Linux Linux affected f2fc6a54585a1be6669613a31fbaba2ecbadcd36 8a4790850e710fd6771e4d2112168ed1dd6c0e54 git Not specified
CNA Linux Linux affected f2fc6a54585a1be6669613a31fbaba2ecbadcd36 fedd2e1630cac920844997227ccbe7b26a76375a git Not specified
CNA Linux Linux affected f2fc6a54585a1be6669613a31fbaba2ecbadcd36 f04733c4dc40c43899c3d1c97afbae5831a3770f git Not specified
CNA Linux Linux affected f2fc6a54585a1be6669613a31fbaba2ecbadcd36 9a18629f2525781f0f3dda7be72b204e4cf77d08 git Not specified
CNA Linux Linux affected f2fc6a54585a1be6669613a31fbaba2ecbadcd36 63d45077b97bb0e0fe0c75931acbbca7a47af141 git Not specified
CNA Linux Linux affected f2fc6a54585a1be6669613a31fbaba2ecbadcd36 ba8bda9a0896746053aa97ac6c3e08168729172c git Not specified
CNA Linux Linux affected 2.6.26 Not specified
CNA Linux Linux unaffected 2.6.26 semver Not specified
CNA Linux Linux unaffected 5.10.253 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.203 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.168 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.131 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.80 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.21 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.11 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/63d45077b97bb0e0fe0c75931acbbca7a47af141 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f04733c4dc40c43899c3d1c97afbae5831a3770f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9a18629f2525781f0f3dda7be72b204e4cf77d08 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fedd2e1630cac920844997227ccbe7b26a76375a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8a4790850e710fd6771e4d2112168ed1dd6c0e54 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/be0e63f3b97bbaf453c542e8a15ba2a536e2ac01 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c1ec36cb3768574b916f20d2d7415fd14fa1bf12 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ba8bda9a0896746053aa97ac6c3e08168729172c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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