CVE-2023-54094
Unknown Unknown - Not Provided
Use-After-Free Vulnerability in Linux Kernel Network skb Segmentation

Publication date: 2025-12-24

Last updated on: 2025-12-24

Assigner: kernel.org

Description
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.
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Meta Information
Published
2025-12-24
Last Modified
2025-12-24
Generated
2026-05-07
AI Q&A
2025-12-24
EPSS Evaluated
2026-05-05
NVD
CVE-2023-54094
EUVD
EUVD-2023-60351
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel 6.4.0
Helpful Resources
Exploitability
CWE
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KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability in the Linux kernel involves skb (socket buffer) corruption during frag list segmentation. Specifically, when rx-gro-list GRO-ed packets are processed via a network bridge to both local input and an egress device, the segmentation operation unsafely writes to cloned skbs that share heads, leading to skb corruption and kernel crashes such as NULL pointer dereferences. The fix involves uncloning the skbs as needed before segmentation to prevent this unsafe write.


How can this vulnerability impact me? :

This vulnerability can cause kernel crashes due to skb corruption, resulting in system instability or denial of service. It may disrupt network packet processing, potentially affecting network performance and reliability on affected Linux systems.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by monitoring kernel logs for specific oops messages related to skb corruption and NULL pointer dereferences. Look for kernel log entries similar to: '[ 62.624003] BUG: kernel NULL pointer dereference, address: 00000000000000c0' and call traces involving __udp_gso_segment and related network functions. You can use the command 'dmesg | grep -i "BUG: kernel NULL pointer dereference"' or 'journalctl -k | grep -i "BUG: kernel NULL pointer dereference"' to find such messages.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation steps include updating the Linux kernel to a version where this vulnerability is fixed, as the issue is resolved by changes that uncloned to-be-segmented skbs. Until an update is applied, consider disabling GRO (Generic Receive Offload) or bridging features that may trigger the vulnerability to reduce risk.


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