[moderation/CI] Re: macvlan: allow source mode devices along with passthru

[syzbot ci <syzbot+ci8d333e09229b69c8@syzkaller.appspotmail.com>]

syzbot ci has tested the following series

[v2] macvlan: allow source mode devices along with passthru
https://lore.kernel.org/all/20260709100512.1383421-1-t.martitz@fritz.com
* [PATCH v2 1/1] macvlan: allow source mode devices along with passthru

and found the following issue:
general protection fault in macvlan_port_release_mac

Full report is available here:
https://ci.syzbot.org/series/2632619d-fb66-47ac-85a1-a781bbb0d57d

***

general protection fault in macvlan_port_release_mac

tree:      net-next
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/netdev/net-next.git
base:      fe3e786ef4eb6e47d2901f568a27bd920477bbe9
arch:      amd64
compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
config:    https://ci.syzbot.org/builds/90f86060-ab12-43d6-a718-5d0f5eb5df09/config
syz repro: https://ci.syzbot.org/findings/d1f12788-51d7-4251-8fc9-6bfda6a1e20a/syz_repro

batman_adv: batadv0: Removing interface: batadv_slave_1
veth1_macvtap: left promiscuous mode
veth0_macvtap: left promiscuous mode
veth1_vlan: left promiscuous mode
veth0_vlan: left promiscuous mode
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000118: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x00000000000008c0-0x00000000000008c7]
CPU: 0 UID: 0 PID: 12 Comm: kworker/u8:0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: netns cleanup_net
RIP: 0010:macvlan_passthru drivers/net/macvlan.c:78 [inline]
RIP: 0010:macvlan_port_release_mac+0x138/0x490 drivers/net/macvlan.c:807
Code: 01 00 00 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 b9 30 ae fb 48 8b 1b 4c 8d b3 c0 08 00 00 4c 89 f0 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 44 02 00 00 45 8b 36 44 89 f6 83 e6 01
RSP: 0018:ffffc90000117500 EFLAGS: 00010206
RAX: 0000000000000118 RBX: 0000000000000000 RCX: ffff888102e98000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000117630 R08: ffffffff9032faf7 R09: 1ffffffff2065f5e
R10: dffffc0000000000 R11: fffffbfff2065f5f R12: dffffc0000000000
R13: 1ffff92000022ea4 R14: 00000000000008c0 R15: ffff88816b068818
FS:  0000000000000000(0000) GS:ffff88818dc23000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb0fefe8158 CR3: 0000000113c9a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 macvlan_port_destroy+0x2eb/0x310 drivers/net/macvlan.c:1343
 unregister_netdevice_many_notify+0x1ad2/0x2150 net/core/dev.c:12464
 unregister_netdevice_many net/core/dev.c:12506 [inline]
 default_device_exit_batch+0x961/0x9e0 net/core/dev.c:13098
 ops_exit_list net/core/net_namespace.c:205 [inline]
 ops_undo_list+0x4b4/0x8d0 net/core/net_namespace.c:252
 cleanup_net+0x572/0x810 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:macvlan_passthru drivers/net/macvlan.c:78 [inline]
RIP: 0010:macvlan_port_release_mac+0x138/0x490 drivers/net/macvlan.c:807
Code: 01 00 00 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 b9 30 ae fb 48 8b 1b 4c 8d b3 c0 08 00 00 4c 89 f0 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 44 02 00 00 45 8b 36 44 89 f6 83 e6 01
RSP: 0018:ffffc90000117500 EFLAGS: 00010206
RAX: 0000000000000118 RBX: 0000000000000000 RCX: ffff888102e98000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000117630 R08: ffffffff9032faf7 R09: 1ffffffff2065f5e
R10: dffffc0000000000 R11: fffffbfff2065f5f R12: dffffc0000000000
R13: 1ffff92000022ea4 R14: 00000000000008c0 R15: ffff88816b068818
FS:  0000000000000000(0000) GS:ffff88818dc23000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33163fff CR3: 0000000175a06000 CR4: 00000000000006f0
----------------
Code disassembly (best guess):
   0:	01 00                	add    %eax,(%rax)
   2:	00 48 89             	add    %cl,-0x77(%rax)
   5:	d8 48 c1             	fmuls  -0x3f(%rax)
   8:	e8 03 42 80 3c       	call   0x3c804210
   d:	20 00                	and    %al,(%rax)
   f:	74 08                	je     0x19
  11:	48 89 df             	mov    %rbx,%rdi
  14:	e8 b9 30 ae fb       	call   0xfbae30d2
  19:	48 8b 1b             	mov    (%rbx),%rbx
  1c:	4c 8d b3 c0 08 00 00 	lea    0x8c0(%rbx),%r14
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 44 02 00 00    	jne    0x27b
  37:	45 8b 36             	mov    (%r14),%r14d
  3a:	44 89 f6             	mov    %r14d,%esi
  3d:	83 e6 01             	and    $0x1,%esi


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@syzkaller.appspotmail.com

---
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