| From bad74ff3e98960478dddc6604fd593027b166ff7 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Wed, 18 Feb 2026 06:09:19 +0000 |
| Subject: bonding: alb: fix UAF in rlb_arp_recv during bond up/down |
| |
| From: Hangbin Liu <liuhangbin@gmail.com> |
| |
| [ Upstream commit e6834a4c474697df23ab9948fd3577b26bf48656 ] |
| |
| 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(). |
| |
| Reported-by: Liang Li <liali@redhat.com> |
| Fixes: 3aba891dde38 ("bonding: move processing of recv handlers into handle_frame()") |
| Reviewed-by: Nikolay Aleksandrov <nikolay@nvidia.com> |
| Acked-by: Jay Vosburgh <jv@jvosburgh.net> |
| Signed-off-by: Hangbin Liu <liuhangbin@gmail.com> |
| Link: https://patch.msgid.link/20260218060919.101574-1-liuhangbin@gmail.com |
| Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/net/bonding/bond_main.c | 6 +++++- |
| 1 file changed, 5 insertions(+), 1 deletion(-) |
| |
| diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c |
| index 27ed164375411..1323a619db4d2 100644 |
| --- a/drivers/net/bonding/bond_main.c |
| +++ b/drivers/net/bonding/bond_main.c |
| @@ -4024,9 +4024,13 @@ static int bond_close(struct net_device *bond_dev) |
| |
| bond_work_cancel_all(bond); |
| bond->send_peer_notif = 0; |
| + WRITE_ONCE(bond->recv_probe, NULL); |
| + |
| + /* Wait for any in-flight RX handlers */ |
| + synchronize_net(); |
| + |
| if (bond_is_lb(bond)) |
| bond_alb_deinitialize(bond); |
| - bond->recv_probe = NULL; |
| |
| if (bond_uses_primary(bond)) { |
| rcu_read_lock(); |
| -- |
| 2.51.0 |
| |
