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In the Linux kernel, the following vulnerability has been resolved:
skbuff: skb_segment, Call zero copy functions before using skbuff frags
Commit bf5c25d60861 ("skbuff: in skb_segment, call zerocopy functions once per nskb") added the call to zero copy functions in skb_segment(). The change introduced a bug in skb_segment() because skb_orphan_frags() may possibly change the number of fragments or allocate new fragments altogether leaving nrfrags and frag to point to the old values. This can cause a panic with stacktrace like the one below.
[ 193.894380] BUG: kernel NULL pointer dereference, address: 00000000000000bc [ 193.895273] CPU: 13 PID: 18164 Comm: vh-net-17428 Kdump: loaded Tainted: G O 5.15.123+ #26 [ 193.903919] RIP: 0010:skb_segment+0xb0e/0x12f0 [ 194.021892] Call Trace: [ 194.027422] <TASK> [ 194.072861] tcp_gso_segment+0x107/0x540 [ 194.082031] inet_gso_segment+0x15c/0x3d0 [ 194.090783] skb_mac_gso_segment+0x9f/0x110 [ 194.095016] __skb_gso_segment+0xc1/0x190 [ 194.103131] netem_enqueue+0x290/0xb10 [sch_netem] [ 194.107071] dev_qdisc_enqueue+0x16/0x70 [ 194.110884] __dev_queue_xmit+0x63b/0xb30 [ 194.121670] bond_start_xmit+0x159/0x380 [bonding] [ 194.128506] dev_hard_start_xmit+0xc3/0x1e0 [ 194.131787] __dev_queue_xmit+0x8a0/0xb30 [ 194.138225] macvlan_start_xmit+0x4f/0x100 [macvlan] [ 194.141477] dev_hard_start_xmit+0xc3/0x1e0 [ 194.144622] sch_direct_xmit+0xe3/0x280 [ 194.147748] __dev_queue_xmit+0x54a/0xb30 [ 194.154131] tap_get_user+0x2a8/0x9c0 [tap] [ 194.157358] tap_sendmsg+0x52/0x8e0 [tap] [ 194.167049] handle_tx_zerocopy+0x14e/0x4c0 [vhost_net] [ 194.173631] handle_tx+0xcd/0xe0 [vhost_net] [ 194.176959] vhost_worker+0x76/0xb0 [vhost] [ 194.183667] kthread+0x118/0x140 [ 194.190358] ret_from_fork+0x1f/0x30 [ 194.193670] </TASK>
In this case calling skb_orphan_frags() updated nr_frags leaving nrfrags local variable in skb_segment() stale. This resulted in the code hitting i >= nrfrags prematurely and trying to move to next frag_skb using list_skb pointer, which was NULL, and caused kernel panic. Move the call to zero copy functions before using frags and nr_frags.
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernel-develUpgrade kernel-livepatch-5.10.196-185.743Upgrade kernel-tools-develUpgrade kernel-debuginfoUpgrade perfUpgrade bpftoolUpgrade kernel-debuginfo-common-aarch64Upgrade kernel-tools-debuginfoUpgrade perf-debuginfoUpgrade python-perf-debuginfoUpgrade python-perfUpgrade kernel-livepatch-5.15.133-86.144Upgrade kernel-debuginfo-common-x86_64Upgrade kernel-toolsUpgrade kernel-headersUpgrade bpftool-debuginfoUpgrade kernel | May 20, 2026 | May 20, 2026 |
| Amazon_linux_2023 | — | Upgrade kernel-tools-debuginfoUpgrade python3-perf-debuginfoUpgrade kernel-debuginfoUpgrade kernel-develUpgrade kernel-libbpf-staticUpgrade kernel-livepatch-6.1.55-75.123Upgrade kernel-debuginfo-common-aarch64Upgrade kernel-debuginfo-common-x86_64Upgrade bpftoolUpgrade bpftool-debuginfoUpgrade kernel-libbpfUpgrade python3-perfUpgrade perfUpgrade kernel-headersUpgrade kernel-toolsUpgrade kernelUpgrade kernel-tools-develUpgrade perf-debuginfoUpgrade kernel-libbpf-devel | Sep 30, 2025 | Sep 17, 2025 |
| Debian | — | Upgrade linux | Sep 19, 2025 | Sep 19, 2025 |
| Huawei Euleros 2_0_sp10 | — | Upgrade kernelUpgrade kernel-tools-libsUpgrade kernel-abi-stablelistsUpgrade python3-perfUpgrade kernel-tools | Jan 15, 2026 | Jan 13, 2026 |
| Huawei Euleros 2_0_sp13 | — | Upgrade bpftoolUpgrade kernelUpgrade kernel-toolsUpgrade kernel-tools-libsUpgrade python3-perfUpgrade kernel-abi-stablelists | Feb 3, 2026 | Jan 30, 2026 |
| Redhat_linux | — | Upgrade kernelUpgrade kernel-rtNo solution exists | Nov 14, 2025 | Sep 17, 2025 |
| Ubuntu | — | Upgrade linux-gcp-5.4Upgrade linux-azure-fipsUpgrade linux-lowlatencyUpgrade linux-gkeUpgrade linux-intel-iotgUpgrade linux-nvidia-tegra-igxUpgrade linux-gcpUpgrade linux-aws-5.4Upgrade linux-ibm-5.15Upgrade linux-kvmUpgrade linux-intel-iot-realtimeUpgrade linux-riscv-5.15Upgrade linux-fipsUpgrade linux-ibmUpgrade linux-xilinx-zynqmpUpgrade linux-nvidiaUpgrade linux-azure-5.15Upgrade linux-gkeopUpgrade linux-hwe-5.4Upgrade linux-intel-iotg-5.15Upgrade linux-gcp-5.15Upgrade linux-oracle-5.4Upgrade linux-realtimeUpgrade linux-raspiUpgrade linux-aws-fipsUpgrade linux-oracle-5.15Upgrade linux-oracleUpgrade linux-ibm-5.4Upgrade linux-raspi-5.4Upgrade linux-lowlatency-hwe-5.15Upgrade linux-azure-5.4Upgrade linux-aws-5.15Upgrade linux-nvidia-tegra-5.15Upgrade linux-awsUpgrade linuxUpgrade linux-iotUpgrade linux-azureUpgrade linux-nvidia-tegraUpgrade linux-bluefieldUpgrade linux-hwe-5.15Upgrade linux-gcp-fipsUpgrade linux-azure-fde | Sep 26, 2025 | Sep 17, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Oct 15, 2025 | Sep 17, 2025 |
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