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

#syz upstream


On Fri, Jul 10, 2026 at 8:47 AM syzbot ci
<[email protected]> wrote:
>
> syzbot ci has tested the following series
>
> [v2] macvlan: allow source mode devices along with passthru
> https://lore.kernel.org/all/[email protected]
> * [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/72476997-558e-41ae-b146-c05346cdd7f6
>
> ***
>
> 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/0c5e2f82-62bd-40bf-a873-66f277607c07/config
> syz repro: https://ci.syzbot.org/findings/d5d14725-5a48-484c-876d-026175d0b21a/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: 1 UID: 0 PID: 13 Comm: kworker/u8:1 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:ffffc90000127500 EFLAGS: 00010206
> RAX: 0000000000000118 RBX: 0000000000000000 RCX: ffff888102ec5940
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
> RBP: ffffc90000127630 R08: ffffffff9032faf7 R09: 1ffffffff2065f5e
> R10: dffffc0000000000 R11: fffffbfff2065f5f R12: dffffc0000000000
> R13: 1ffff92000024ea4 R14: 00000000000008c0 R15: ffff888109b28818
> FS:  0000000000000000(0000) GS:ffff8882a9223000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ffefe7250d8 CR3: 000000000e746000 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:ffffc90000127500 EFLAGS: 00010206
> RAX: 0000000000000118 RBX: 0000000000000000 RCX: ffff888102ec5940
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
> RBP: ffffc90000127630 R08: ffffffff9032faf7 R09: 1ffffffff2065f5e
> R10: dffffc0000000000 R11: fffffbfff2065f5f R12: dffffc0000000000
> R13: 1ffff92000024ea4 R14: 00000000000008c0 R15: ffff888109b28818
> FS:  0000000000000000(0000) GS:ffff8882a9223000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ffefe7250d8 CR3: 000000000e746000 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: [email protected]
>
> ---
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>
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-- 
Ⲡⲟⲓⲙⲏⲛ Ⲅⲉⲱⲣⲅⲓⲟⲥ - Pimyn Girgis
Software Engineer
Kernel Dynamic Analysis
[email protected]