UBUNTU-CVE-2026-74684: Null Pointer Dereference
In the Linux kernel, the following vulnerability has been resolved: net: tap: set skb->dev before parsing virtio net header in tapgetuserxdp() The commit 4f61f133f354 ("net: tap: NULL pointer derefence in devparseheaderprotocol when skb->dev is null") fixed a crash in tapgetuser() by assigning skb->dev before calling tunvnethdrtoskb(). This is required because virtionethdrtoskb() may invoke devparseheaderprotocol(), which dereferences skb->dev. Without the assignment, a NULL pointer dereference can occur. However, tapgetuserxdp() still parses the virtio-net header before assigning skb->dev. When the vhost TX path passes an XDP buffer containing a GSO virtio-net header but the protocol is set to zero on purpose, tunvnethdrtoskb() can reach devparseheaderprotocol() while skb->dev is still NULL, resulting in a crash. Fix this by looking up the tap device and assigning skb->dev before calling tunvnethdrtoskb(), matching the ordering already used in tapgetuser(). Preserve the existing RCU read-side critical section across devqueuexmit().
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
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ubuntu/linux-nvidia-tegrato a version that resolves this vulnerability.Fixed in 6.8.0-1036.39 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Compensating control
In tap_get_user_xdp(), look up the tap device and assign skb->dev before calling tun_vnet_hdr_to_skb() (and before virtio_net_hdr_to_skb() can invoke dev_parse_header_protocol()); preserve the existing RCU read-side critical section across dev_queue_xmit().