In the Linux kernel, the following vulnerability has been resolved:
net: prevent skb corruption on frag list segmentation
Ian reported several skb corruptions triggered by rx-gro-list, collecting different oops alike:
[ 62.624003] BUG: kernel NULL pointer dereference, address: 00000000000000c0 [ 62.631083] #PF: supervisor read access in kernel mode [ 62.636312] #PF: error_code(0x0000) - not-present page [ 62.641541] PGD 0 P4D 0 [ 62.644174] Oops: 0000 [#1] PREEMPT SMP NOPTI [ 62.648629] CPU: 1 PID: 913 Comm: napi/eno2-79 Not tainted 6.4.0 #364 [ 62.655162] Hardware name: Supermicro Super Server/A2SDi-12C-HLN4F, BIOS 1.7a 10/13/2022 [ 62.663344] RIP: 0010:__udp_gso_segment (./include/linux/skbuff.h:2858 ./include/linux/udp.h:23 net/ipv4/udp_offload.c:228 net/ipv4/udp_offload.c:261 net/ipv4/udp_offload.c:277) [ 62.687193] RSP: 0018:ffffbd3a83b4f868 EFLAGS: 00010246 [ 62.692515] RAX: 00000000000000ce RBX: 0000000000000000 RCX: 0000000000000000 [ 62.699743] RDX: ffffa124def8a000 RSI: 0000000000000079 RDI: ffffa125952a14d4 [ 62.706970] RBP: ffffa124def8a000 R08: 0000000000000022 R09: 00002000001558c9 [ 62.714199] R10: 0000000000000000 R11: 00000000be554639 R12: 00000000000000e2 [ 62.721426] R13: ffffa125952a1400 R14: ffffa125952a1400 R15: 00002000001558c9 [ 62.728654] FS: 0000000000000000(0000) GS:ffffa127efa40000(0000) knlGS:0000000000000000 [ 62.736852] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 62.742702] CR2: 00000000000000c0 CR3: 00000001034b0000 CR4: 00000000003526e0 [ 62.749948] Call Trace: [ 62.752498] <TASK> [ 62.779267] inet_gso_segment (net/ipv4/af_inet.c:1398) [ 62.787605] skb_mac_gso_segment (net/core/gro.c:141) [ 62.791906] __skb_gso_segment (net/core/dev.c:3403 (discriminator 2)) [ 62.800492] validate_xmit_skb (./include/linux/netdevice.h:4862 net/core/dev.c:3659) [ 62.804695] validate_xmit_skb_list (net/core/dev.c:3710) [ 62.809158] sch_direct_xmit (net/sched/sch_generic.c:330) [ 62.813198] __dev_queue_xmit (net/core/dev.c:3805 net/core/dev.c:4210) net/netfilter/core.c:626) [ 62.821093] br_dev_queue_push_xmit (net/bridge/br_forward.c:55) [ 62.825652] maybe_deliver (net/bridge/br_forward.c:193) [ 62.829420] br_flood (net/bridge/br_forward.c:233) [ 62.832758] br_handle_frame_finish (net/bridge/br_input.c:215) [ 62.837403] br_handle_frame (net/bridge/br_input.c:298 net/bridge/br_input.c:416) [ 62.851417] __netif_receive_skb_core.constprop.0 (net/core/dev.c:5387) [ 62.866114] __netif_receive_skb_list_core (net/core/dev.c:5570) [ 62.871367] netif_receive_skb_list_internal (net/core/dev.c:5638 net/core/dev.c:5727) [ 62.876795] napi_complete_done (./include/linux/list.h:37 ./include/net/gro.h:434 ./include/net/gro.h:429 net/core/dev.c:6067) [ 62.881004] ixgbe_poll (drivers/net/ethernet/intel/ixgbe/ixgbe_main.c:3191) [ 62.893534] __napi_poll (net/core/dev.c:6498) [ 62.897133] napi_threaded_poll (./include/linux/netpoll.h:89 net/core/dev.c:6640) [ 62.905276] kthread (kernel/kthread.c:379) [ 62.913435] ret_from_fork (arch/x86/entry/entry_64.S:314) [ 62.917119] </TASK>
In the critical scenario, rx-gro-list GRO-ed packets are fed, via a bridge, both to the local input path and to an egress device (tun).
The segmentation of such packets unsafely writes to the cloned skbs with shared heads.
This change addresses the issue by uncloning as needed the to-be-segmented skbs.
CVSS Details
- CVSS 3.1 Base Score: 9.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernel-tools-develUpgrade kernel-toolsUpgrade kernelUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-livepatch-5.10.192-182.736Upgrade bpftoolUpgrade kernel-debuginfoUpgrade python-perfUpgrade kernel-develUpgrade python-perf-debuginfoUpgrade kernel-livepatch-5.15.122-77.145Upgrade bpftool-debuginfoUpgrade kernel-headersUpgrade kernel-debuginfo-common-aarch64Upgrade perf-debuginfoUpgrade kernel-tools-debuginfoUpgrade perf | May 20, 2026 | May 20, 2026 |
| Amazon_linux_2023 | — | Upgrade kernel-debuginfoUpgrade perf-debuginfoUpgrade kernel-libbpfUpgrade kernel-livepatch-6.1.41-63.109Upgrade kernel-tools-debuginfoUpgrade perfUpgrade bpftool-debuginfoUpgrade kernel-debuginfo-common-aarch64Upgrade kernel-headersUpgrade kernel-libbpf-develUpgrade kernel-toolsUpgrade kernel-develUpgrade kernelUpgrade kernel-libbpf-staticUpgrade bpftoolUpgrade python3-perfUpgrade python3-perf-debuginfoUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-tools-devel | Feb 20, 2026 | Dec 24, 2025 |
| Debian | — | Upgrade linux | Dec 29, 2025 | Dec 29, 2025 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Dec 24, 2025 |
| Ubuntu | — | Upgrade linuxUpgrade linux-oracle-5.15Upgrade linux-azure-5.15Upgrade linux-ibmUpgrade linux-xilinx-zynqmpUpgrade linux-intel-iot-realtimeUpgrade linux-gcpUpgrade linux-oracleUpgrade linux-gkeopUpgrade linux-nvidiaUpgrade linux-ibm-5.15Upgrade linux-nvidia-tegra-igxUpgrade linux-lowlatencyUpgrade linux-aws-5.15Upgrade linux-raspiUpgrade linux-lowlatency-hwe-5.15Upgrade linux-riscv-5.15Upgrade linux-intel-iotg-5.15Upgrade linux-kvmUpgrade linux-nvidia-tegra-5.15Upgrade linux-azureUpgrade linux-intel-iotgUpgrade linux-gcp-5.15Upgrade linux-bluefieldUpgrade linux-hwe-5.15Upgrade linux-realtimeUpgrade linux-awsUpgrade linux-gkeUpgrade linux-nvidia-tegra | Jan 6, 2026 | Dec 24, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | Dec 24, 2025 |
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