6.6-stable review patch. If anyone has any objections, please let me know.
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From: Kuniyuki Iwashima kuniyu@amazon.com
[ Upstream commit 4ccacf86491d33d2486b62d4d44864d7101b299d ]
Brad Spengler reported the list_del() corruption splat in gtp_net_exit_batch_rtnl(). [0]
Commit eb28fd76c0a0 ("gtp: Destroy device along with udp socket's netns dismantle.") added the for_each_netdev() loop in gtp_net_exit_batch_rtnl() to destroy devices in each netns as done in geneve and ip tunnels.
However, this could trigger ->dellink() twice for the same device during ->exit_batch_rtnl().
Say we have two netns A & B and gtp device B that resides in netns B but whose UDP socket is in netns A.
1. cleanup_net() processes netns A and then B.
2. gtp_net_exit_batch_rtnl() finds the device B while iterating netns A's gn->gtp_dev_list and calls ->dellink().
[ device B is not yet unlinked from netns B as unregister_netdevice_many() has not been called. ]
3. gtp_net_exit_batch_rtnl() finds the device B while iterating netns B's for_each_netdev() and calls ->dellink().
gtp_dellink() cleans up the device's hash table, unlinks the dev from gn->gtp_dev_list, and calls unregister_netdevice_queue().
Basically, calling gtp_dellink() multiple times is fine unless CONFIG_DEBUG_LIST is enabled.
Let's remove for_each_netdev() in gtp_net_exit_batch_rtnl() and delegate the destruction to default_device_exit_batch() as done in bareudp.
[0]: list_del corruption, ffff8880aaa62c00->next (autoslab_size_M_dev_P_net_core_dev_11127_8_1328_8_S_4096_A_64_n_139+0xc00/0x1000 [slab object]) is LIST_POISON1 (ffffffffffffff02) (prev is 0xffffffffffffff04) kernel BUG at lib/list_debug.c:58! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 1 UID: 0 PID: 1804 Comm: kworker/u8:7 Tainted: G T 6.12.13-grsec-full-20250211091339 #1 Tainted: [T]=RANDSTRUCT Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Workqueue: netns cleanup_net RIP: 0010:[<ffffffff84947381>] __list_del_entry_valid_or_report+0x141/0x200 lib/list_debug.c:58 Code: c2 76 91 31 c0 e8 9f b1 f7 fc 0f 0b 4d 89 f0 48 c7 c1 02 ff ff ff 48 89 ea 48 89 ee 48 c7 c7 e0 c2 76 91 31 c0 e8 7f b1 f7 fc <0f> 0b 4d 89 e8 48 c7 c1 04 ff ff ff 48 89 ea 48 89 ee 48 c7 c7 60 RSP: 0018:fffffe8040b4fbd0 EFLAGS: 00010283 RAX: 00000000000000cc RBX: dffffc0000000000 RCX: ffffffff818c4054 RDX: ffffffff84947381 RSI: ffffffff818d1512 RDI: 0000000000000000 RBP: ffff8880aaa62c00 R08: 0000000000000001 R09: fffffbd008169f32 R10: fffffe8040b4f997 R11: 0000000000000001 R12: a1988d84f24943e4 R13: ffffffffffffff02 R14: ffffffffffffff04 R15: ffff8880aaa62c08 RBX: kasan shadow of 0x0 RCX: __wake_up_klogd.part.0+0x74/0xe0 kernel/printk/printk.c:4554 RDX: __list_del_entry_valid_or_report+0x141/0x200 lib/list_debug.c:58 RSI: vprintk+0x72/0x100 kernel/printk/printk_safe.c:71 RBP: autoslab_size_M_dev_P_net_core_dev_11127_8_1328_8_S_4096_A_64_n_139+0xc00/0x1000 [slab object] RSP: process kstack fffffe8040b4fbd0+0x7bd0/0x8000 [kworker/u8:7+netns 1804 ] R09: kasan shadow of process kstack fffffe8040b4f990+0x7990/0x8000 [kworker/u8:7+netns 1804 ] R10: process kstack fffffe8040b4f997+0x7997/0x8000 [kworker/u8:7+netns 1804 ] R15: autoslab_size_M_dev_P_net_core_dev_11127_8_1328_8_S_4096_A_64_n_139+0xc08/0x1000 [slab object] FS: 0000000000000000(0000) GS:ffff888116000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000748f5372c000 CR3: 0000000015408000 CR4: 00000000003406f0 shadow CR4: 00000000003406f0 Stack: 0000000000000000 ffffffff8a0c35e7 ffffffff8a0c3603 ffff8880aaa62c00 ffff8880aaa62c00 0000000000000004 ffff88811145311c 0000000000000005 0000000000000001 ffff8880aaa62000 fffffe8040b4fd40 ffffffff8a0c360d Call Trace: <TASK> [<ffffffff8a0c360d>] __list_del_entry_valid include/linux/list.h:131 [inline] fffffe8040b4fc28 [<ffffffff8a0c360d>] __list_del_entry include/linux/list.h:248 [inline] fffffe8040b4fc28 [<ffffffff8a0c360d>] list_del include/linux/list.h:262 [inline] fffffe8040b4fc28 [<ffffffff8a0c360d>] gtp_dellink+0x16d/0x360 drivers/net/gtp.c:1557 fffffe8040b4fc28 [<ffffffff8a0d0404>] gtp_net_exit_batch_rtnl+0x124/0x2c0 drivers/net/gtp.c:2495 fffffe8040b4fc88 [<ffffffff8e705b24>] cleanup_net+0x5a4/0xbe0 net/core/net_namespace.c:635 fffffe8040b4fcd0 [<ffffffff81754c97>] process_one_work+0xbd7/0x2160 kernel/workqueue.c:3326 fffffe8040b4fd88 [<ffffffff81757195>] process_scheduled_works kernel/workqueue.c:3407 [inline] fffffe8040b4fec0 [<ffffffff81757195>] worker_thread+0x6b5/0xfa0 kernel/workqueue.c:3488 fffffe8040b4fec0 [<ffffffff817782a0>] kthread+0x360/0x4c0 kernel/kthread.c:397 fffffe8040b4ff78 [<ffffffff814d8594>] ret_from_fork+0x74/0xe0 arch/x86/kernel/process.c:172 fffffe8040b4ffb8 [<ffffffff8110f509>] ret_from_fork_asm+0x29/0xc0 arch/x86/entry/entry_64.S:399 fffffe8040b4ffe8 </TASK> Modules linked in:
Fixes: eb28fd76c0a0 ("gtp: Destroy device along with udp socket's netns dismantle.") Reported-by: Brad Spengler spender@grsecurity.net Signed-off-by: Kuniyuki Iwashima kuniyu@amazon.com Link: https://patch.msgid.link/20250217203705.40342-2-kuniyu@amazon.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/gtp.c | 5 ----- 1 file changed, 5 deletions(-)
diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 47238c3ec82e7..55160a5fc90fc 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -1895,11 +1895,6 @@ static void __net_exit gtp_net_exit_batch_rtnl(struct list_head *net_list, list_for_each_entry(net, net_list, exit_list) { struct gtp_net *gn = net_generic(net, gtp_net_id); struct gtp_dev *gtp, *gtp_next; - struct net_device *dev; - - for_each_netdev(net, dev) - if (dev->rtnl_link_ops == >p_link_ops) - gtp_dellink(dev, dev_to_kill);
list_for_each_entry_safe(gtp, gtp_next, &gn->gtp_dev_list, list) gtp_dellink(gtp->dev, dev_to_kill);