CVE-2026-45970
Analyzed Analyzed - Analysis Complete
Use-After-Free in Linux Kernel bonding ALB Module

Publication date: 2026-05-27

Last updated on: 2026-06-16

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: bonding: alb: fix UAF in rlb_arp_recv during bond up/down The ALB RX path may access rx_hashtbl concurrently with bond teardown. During rapid bond up/down cycles, rlb_deinitialize() frees rx_hashtbl while RX handlers are still running, leading to a null pointer dereference detected by KASAN. However, the root cause is that rlb_arp_recv() can still be accessed after setting recv_probe to NULL, which is actually a use-after-free (UAF) issue. That is the reason for using the referenced commit in the Fixes tag. [ 214.174138] Oops: general protection fault, probably for non-canonical address 0xdffffc000000001d: 0000 [#1] SMP KASAN PTI [ 214.186478] KASAN: null-ptr-deref in range [0x00000000000000e8-0x00000000000000ef] [ 214.194933] CPU: 30 UID: 0 PID: 2375 Comm: ping Kdump: loaded Not tainted 6.19.0-rc8+ #2 PREEMPT(voluntary) [ 214.205907] Hardware name: Dell Inc. PowerEdge R730/0WCJNT, BIOS 2.14.0 01/14/2022 [ 214.214357] RIP: 0010:rlb_arp_recv+0x505/0xab0 [bonding] [ 214.220320] Code: 0f 85 2b 05 00 00 48 b8 00 00 00 00 00 fc ff df 40 0f b6 ed 48 c1 e5 06 49 03 ad 78 01 00 00 48 8d 7d 28 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 06 0f 8e 12 05 00 00 80 7d 28 00 0f 84 8c 00 [ 214.241280] RSP: 0018:ffffc900073d8870 EFLAGS: 00010206 [ 214.247116] RAX: dffffc0000000000 RBX: ffff888168556822 RCX: ffff88816855681e [ 214.255082] RDX: 000000000000001d RSI: dffffc0000000000 RDI: 00000000000000e8 [ 214.263048] RBP: 00000000000000c0 R08: 0000000000000002 R09: ffffed11192021c8 [ 214.271013] R10: ffff8888c9010e43 R11: 0000000000000001 R12: 1ffff92000e7b119 [ 214.278978] R13: ffff8888c9010e00 R14: ffff888168556822 R15: ffff888168556810 [ 214.286943] FS: 00007f85d2d9cb80(0000) GS:ffff88886ccb3000(0000) knlGS:0000000000000000 [ 214.295966] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 214.302380] CR2: 00007f0d047b5e34 CR3: 00000008a1c2e002 CR4: 00000000001726f0 [ 214.310347] Call Trace: [ 214.313070] <IRQ> [ 214.315318] ? __pfx_rlb_arp_recv+0x10/0x10 [bonding] [ 214.320975] bond_handle_frame+0x166/0xb60 [bonding] [ 214.326537] ? __pfx_bond_handle_frame+0x10/0x10 [bonding] [ 214.332680] __netif_receive_skb_core.constprop.0+0x576/0x2710 [ 214.339199] ? __pfx_arp_process+0x10/0x10 [ 214.343775] ? sched_balance_find_src_group+0x98/0x630 [ 214.349513] ? __pfx___netif_receive_skb_core.constprop.0+0x10/0x10 [ 214.356513] ? arp_rcv+0x307/0x690 [ 214.360311] ? __pfx_arp_rcv+0x10/0x10 [ 214.364499] ? __lock_acquire+0x58c/0xbd0 [ 214.368975] __netif_receive_skb_one_core+0xae/0x1b0 [ 214.374518] ? __pfx___netif_receive_skb_one_core+0x10/0x10 [ 214.380743] ? lock_acquire+0x10b/0x140 [ 214.385026] process_backlog+0x3f1/0x13a0 [ 214.389502] ? process_backlog+0x3aa/0x13a0 [ 214.394174] __napi_poll.constprop.0+0x9f/0x370 [ 214.399233] net_rx_action+0x8c1/0xe60 [ 214.403423] ? __pfx_net_rx_action+0x10/0x10 [ 214.408193] ? lock_acquire.part.0+0xbd/0x260 [ 214.413058] ? sched_clock_cpu+0x6c/0x540 [ 214.417540] ? mark_held_locks+0x40/0x70 [ 214.421920] handle_softirqs+0x1fd/0x860 [ 214.426302] ? __pfx_handle_softirqs+0x10/0x10 [ 214.431264] ? __neigh_event_send+0x2d6/0xf50 [ 214.436131] do_softirq+0xb1/0xf0 [ 214.439830] </IRQ> The issue is reproducible by repeatedly running ip link set bond0 up/down while receiving ARP messages, where rlb_arp_recv() can race with rlb_deinitialize() and dereference a freed rx_hashtbl entry. Fix this by setting recv_probe to NULL and then calling synchronize_net() to wait for any concurrent RX processing to finish. This ensures that no RX handler can access rx_hashtbl after it is freed in bond_alb_deinitialize().
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Meta Information
Published
2026-05-27
Last Modified
2026-06-16
Generated
2026-06-16
AI Q&A
2026-05-27
EPSS Evaluated
2026-06-15
NVD
CVE-2026-45970
EUVD
EUVD-2026-32254
Affected Vendors & Products
Showing 7 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 6.13 (inc) to 6.18.14 (exc)
linux linux_kernel From 6.19 (inc) to 6.19.4 (exc)
linux linux_kernel From 6.2 (inc) to 6.6.128 (exc)
linux linux_kernel From 6.7 (inc) to 6.12.75 (exc)
linux linux_kernel From 5.11 (inc) to 5.15.202 (exc)
linux linux_kernel From 5.16 (inc) to 6.1.165 (exc)
linux linux_kernel From 3.0 (inc) to 5.10.252 (exc)
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-416 The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
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Executive Summary

This vulnerability is a use-after-free (UAF) issue in the Linux kernel's bonding driver, specifically in the ALB (Adaptive Load Balancing) RX path. During rapid bond interface up/down cycles, the function rlb_deinitialize() frees a data structure called rx_hashtbl while RX handlers are still running. This leads to a null pointer dereference detected by KASAN (Kernel Address Sanitizer). The root cause is that the function rlb_arp_recv() can still be accessed after its recv_probe pointer is set to NULL, causing it to access freed memory.

The issue can be reproduced by repeatedly running 'ip link set bond0 up/down' while receiving ARP messages, causing a race condition between rlb_arp_recv() and rlb_deinitialize(). The fix involves setting recv_probe to NULL and then calling synchronize_net() to ensure no RX handlers access rx_hashtbl after it is freed.

Impact Analysis

This vulnerability can cause a kernel crash due to a null pointer dereference, leading to a general protection fault. This can result in system instability or denial of service (DoS) on affected Linux systems using the bonding driver with ALB enabled.

Because the issue occurs during rapid bond interface up/down cycles while processing ARP messages, it may be triggered in environments with dynamic network interface configurations, potentially disrupting network connectivity.

Detection Guidance

This vulnerability can be detected by observing kernel logs for specific error messages related to the bonding module. Look for kernel oops or KASAN (Kernel Address Sanitizer) reports indicating a null pointer dereference in rlb_arp_recv during bond up/down operations.

  • Check kernel logs using: dmesg | grep -i 'bonding\|rlb_arp_recv\|KASAN\|null-ptr-deref'
  • Monitor for general protection faults or null pointer dereferences related to bonding during rapid bond interface up/down cycles.
  • Reproduce the issue by running the command repeatedly: ip link set bond0 up; ip link set bond0 down while ARP traffic is present, then check dmesg for errors.
Mitigation Strategies

To mitigate this vulnerability immediately, avoid rapid cycling of bond interfaces (bond up/down) especially when ARP traffic is present, as this triggers the use-after-free condition.

Apply the patch or update the Linux kernel to a version that includes the fix which sets recv_probe to NULL and calls synchronize_net() to ensure no RX handlers access freed memory.

If updating the kernel is not immediately possible, minimize bond interface state changes and monitor kernel logs for related errors.

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