HIGH
bonding Slave Array UAF
CVE-2026-23171
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
KernelScan AI7.8HIGH
01Description
In the Linux kernel, the following vulnerability has been resolved: bonding: fix use-after-free due to enslave fail after slave array update Fix a use-after-free which happens due to enslave failure after the new slave has been added to the array. Since the new slave can be used for Tx immediately, we can use it after it has been freed by the enslave error cleanup path which frees the allocated slave memory. Slave update array is supposed to be called last when further enslave failures are not expected. Move it after xdp setup to avoid any problems. It is very easy to reproduce the problem with a simple xdp_pass prog: ip l add bond1 type bond mode balance-xor ip l set bond1 up ip l set dev bond1 xdp object xdp_pass.o sec xdp_pass ip l add dumdum type dummy Then run in parallel: while :; do ip l set dumdum master bond1 1>/dev/null 2>&1; done; mausezahn bond1 -a own -b rand -A rand -B 1.1.1.1 -c 0 -t tcp "dp=1-1023, flags=syn" The crash happens almost immediately: [ 605.602850] Oops: general protection fault, probably for non-canonical address 0xe0e6fc2460000137: 0000 [#1] SMP KASAN NOPTI [ 605.602916] KASAN: maybe wild-memory-access in range [0x07380123000009b8-0x07380123000009bf] [ 605.602946] CPU: 0 UID: 0 PID: 2445 Comm: mausezahn Kdump: loaded Tainted: G B 6.19.0-rc6+ #21 PREEMPT(voluntary) [ 605.602979] Tainted: [B]=BAD_PAGE [ 605.602998] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 605.603032] RIP: 0010:netdev_core_pick_tx+0xcd/0x210 [ 605.603063] Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 3e 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 6b 08 49 8d 7d 30 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 25 01 00 00 49 8b 45 30 4c 89 e2 48 89 ee 48 89 [ 605.603111] RSP: 0018:ffff88817b9af348 EFLAGS: 00010213 [ 605.603145] RAX: dffffc0000000000 RBX: ffff88817d28b420 RCX: 0000000000000000 [ 605.603172] RDX: 00e7002460000137 RSI: 0000000000000008 RDI: 07380123000009be [ 605.603199] RBP: ffff88817b541a00 R08: 0000000000000001 R09: fffffbfff3ed8c0c [ 605.603226] R10: ffffffff9f6c6067 R11: 0000000000000001 R12: 0000000000000000 [ 605.603253] R13: 073801230000098e R14: ffff88817d28b448 R15: ffff88817b541a84 [ 605.603286] FS: 00007f6570ef67c0(0000) GS:ffff888221dfa000(0000) knlGS:0000000000000000 [ 605.603319] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 605.603343] CR2: 00007f65712fae40 CR3: 000000011371b000 CR4: 0000000000350ef0 [ 605.603373] Call Trace: [ 605.603392] <TASK> [ 605.603410] __dev_queue_xmit+0x448/0x32a0 [ 605.603434] ? __pfx_vprintk_emit+0x10/0x10 [ 605.603461] ? __pfx_vprintk_emit+0x10/0x10 [ 605.603484] ? __pfx___dev_queue_xmit+0x10/0x10 [ 605.603507] ? bond_start_xmit+0xbfb/0xc20 [bonding] [ 605.603546] ? _printk+0xcb/0x100 [ 605.603566] ? __pfx__printk+0x10/0x10 [ 605.603589] ? bond_start_xmit+0xbfb/0xc20 [bonding] [ 605.603627] ? add_taint+0x5e/0x70 [ 605.603648] ? add_taint+0x2a/0x70 [ 605.603670] ? end_report.cold+0x51/0x75 [ 605.603693] ? bond_start_xmit+0xbfb/0xc20 [bonding] [ 605.603731] bond_start_xmit+0x623/0xc20 [bonding]
02KernelScan AI Analysis
Risk summary
A local attacker with network configuration privileges can trigger a use-after-free vulnerability in the bonding driver by repeatedly enslaving devices while generating traffic. This can lead to kernel crashes and potential privilege escalation through memory corruption.
Vulnerability analysis
Root Cause: In the bonding driver's slave enslavement process, the slave array is updated too early in the sequence, making the new slave immediately available for TX operations. If the enslavement fails after this point (specifically during XDP setup), the error cleanup path frees the slave memory while the slave is still referenced in the array and can be used by concurrent TX operations.
Attack Surface: Local attack surface requiring the ability to configure network interfaces and load XDP programs. The vulnerability is triggered by repeatedly attempting to enslave network devices to a bond interface while simultaneously generating network traffic through the bond interface.
Fix Mechanism: The patch moves the `bond_update_slave_arr()` call to after the XDP setup phase, ensuring that slaves are only added to the active array after all potential failure points have been passed. This prevents the race condition where freed slave memory could be accessed during packet transmission.
03Fix Versions
| Branch | Fixed in | Patch commit |
|---|---|---|
| 6.12 | 6.12.90 | 2889d92c5f72 |
| 6.18 | 6.18.9 | bd25b092a06a |
| 6.6 | 6.6.140 | 172dcb67dd35 |
| mainline | 6.19 | e9acda52fd2e |