Re: [moderation/CI] Re: netfilter: flowtable: tear down HW offloaded flows on FIB route changes

#syz upstream


On Thu, Jul 9, 2026 at 9:55 PM syzbot ci
<[email protected]> wrote:
>
> syzbot ci has tested the following series
>
> [v1] netfilter: flowtable: tear down HW offloaded flows on FIB route changes
> https://lore.kernel.org/all/[email protected]
> * [PATCH nf] netfilter: flowtable: tear down HW offloaded flows on FIB route changes
>
> and found the following issue:
> general protection fault in net_generic
>
> Full report is available here:
> https://ci.syzbot.org/series/75cd5a68-8e8e-41ef-9da6-dea3554407a7
>
> ***
>
> general protection fault in net_generic
>
> tree:      nf
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/netfilter/nf.git
> base:      60444706aa17616efc03190d099ac347e28b3d0a
> 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/b941607c-6459-4d25-8127-6c11f2a37ef0/config
> syz repro: https://ci.syzbot.org/findings/93de0afd-01d4-4d54-9d3f-13094335f314/syz_repro
>
> Oops: general protection fault, probably for non-canonical address 0xdffffc00000002c8: 0000 [#1] SMP KASAN PTI
> KASAN: probably user-memory-access in range [0x0000000000001640-0x0000000000001647]
> CPU: 1 UID: 0 PID: 5813 Comm: syz.2.19 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
> RIP: 0010:net_generic+0xd4/0x240 include/net/netns/generic.h:46
> Code: 8c be 4a 03 00 00 48 c7 c2 c0 83 e0 8c e8 14 1b 09 f8 49 bf 00 00 00 00 00 fc ff df 49 81 c6 40 16 00 00 4c 89 f0 48 c1 e8 03 <42> 80 3c 38 00 74 08 4c 89 f7 e8 0d a4 9a f8 4d 8b 26 e8 45 e8 1b
> RSP: 0018:ffffc90003bde998 EFLAGS: 00010202
> RAX: 00000000000002c8 RBX: ffffffff8999417e RCX: ffff8881699c5940
> RDX: 0000000000000000 RSI: ffffffff8c2ab760 RDI: ffffffff8c2ab720
> RBP: 0000000000000005 R08: ffffffff8999417e R09: 0000000000000000
> R10: 0000000000000000 R11: ffffffff8e959c20 R12: ffff8881b1679870
> R13: dffffc0000000000 R14: 0000000000001640 R15: dffffc0000000000
> FS:  00007ff6de31c6c0(0000) GS:ffff8882a921d000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ff6dd272780 CR3: 000000016bc8e000 CR4: 00000000000006f0
> Call Trace:
>  <TASK>
>  fib_seq_sum+0x29/0x280 net/core/fib_notifier.c:43
>  register_fib_notifier+0x49/0x360 net/core/fib_notifier.c:106
>  nf_flow_table_init+0x34a/0x460 net/netfilter/nf_flow_table_core.c:888
>  tcf_ct_flow_table_get+0x13b6/0x1f40 net/sched/act_ct.c:352
>  tcf_ct_init+0x6bd/0xb10 net/sched/act_ct.c:1423
>  tcf_action_init_1+0x4ba/0x740 net/sched/act_api.c:1433
>  tcf_action_init+0x30e/0xb10 net/sched/act_api.c:1508
>  tcf_action_add net/sched/act_api.c:2106 [inline]
>  tc_ctl_action+0x43b/0xc70 net/sched/act_api.c:2163
>  rtnetlink_rcv_msg+0x7b9/0xc00 net/core/rtnetlink.c:7085
>  netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
>  netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
>  netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
>  netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
>  sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
>  __sock_sendmsg net/socket.c:790 [inline]
>  ____sys_sendmsg+0x54e/0x850 net/socket.c:2684
>  ___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
>  __sys_sendmsg net/socket.c:2770 [inline]
>  __do_sys_sendmsg net/socket.c:2775 [inline]
>  __se_sys_sendmsg net/socket.c:2773 [inline]
>  __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7ff6dd39ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ff6de31c028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00007ff6dd615fa0 RCX: 00007ff6dd39ce59
> RDX: 0000000000000040 RSI: 0000200000000080 RDI: 0000000000000003
> RBP: 00007ff6dd432e6f R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ff6dd616038 R14: 00007ff6dd615fa0 R15: 00007ffd83f8d058
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:net_generic+0xd4/0x240 include/net/netns/generic.h:46
> Code: 8c be 4a 03 00 00 48 c7 c2 c0 83 e0 8c e8 14 1b 09 f8 49 bf 00 00 00 00 00 fc ff df 49 81 c6 40 16 00 00 4c 89 f0 48 c1 e8 03 <42> 80 3c 38 00 74 08 4c 89 f7 e8 0d a4 9a f8 4d 8b 26 e8 45 e8 1b
> RSP: 0018:ffffc90003bde998 EFLAGS: 00010202
> RAX: 00000000000002c8 RBX: ffffffff8999417e RCX: ffff8881699c5940
> RDX: 0000000000000000 RSI: ffffffff8c2ab760 RDI: ffffffff8c2ab720
> RBP: 0000000000000005 R08: ffffffff8999417e R09: 0000000000000000
> R10: 0000000000000000 R11: ffffffff8e959c20 R12: ffff8881b1679870
> R13: dffffc0000000000 R14: 0000000000001640 R15: dffffc0000000000
> FS:  00007ff6de31c6c0(0000) GS:ffff8882a921d000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ff6dd3ea540 CR3: 000000016bc8e000 CR4: 00000000000006f0
> ----------------
> Code disassembly (best guess):
>    0:   8c be 4a 03 00 00       mov    %?,0x34a(%rsi)
>    6:   48 c7 c2 c0 83 e0 8c    mov    $0xffffffff8ce083c0,%rdx
>    d:   e8 14 1b 09 f8          call   0xf8091b26
>   12:   49 bf 00 00 00 00 00    movabs $0xdffffc0000000000,%r15
>   19:   fc ff df
>   1c:   49 81 c6 40 16 00 00    add    $0x1640,%r14
>   23:   4c 89 f0                mov    %r14,%rax
>   26:   48 c1 e8 03             shr    $0x3,%rax
> * 2a:   42 80 3c 38 00          cmpb   $0x0,(%rax,%r15,1) <-- trapping instruction
>   2f:   74 08                   je     0x39
>   31:   4c 89 f7                mov    %r14,%rdi
>   34:   e8 0d a4 9a f8          call   0xf89aa446
>   39:   4d 8b 26                mov    (%r14),%r12
>   3c:   e8                      .byte 0xe8
>   3d:   45                      rex.RB
>   3e:   e8                      .byte 0xe8
>   3f:   1b                      .byte 0x1b
>
>
> ***
>
> 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]
>
> ---
> This report is generated by a bot. It may contain errors.
> syzbot ci engineers can be reached at [email protected].
>
> To test a patch for this bug, please reply with `#syz test`
> (should be on a separate line).
>
> The patch should be attached to the email.
> Note: arguments like custom git repos and branches are not supported.
>
> The email will later be sent to:
> [[email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected]]
>
> If the report looks fine to you, reply with:
> #syz upstream
>
> If the report is a false positive, reply with
> #syz invalid
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-upstream-moderation" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> To view this discussion visit https://groups.google.com/d/msgid/syzkaller-upstream-moderation/6a4ffcb0.c76b52dc.2a15e.0000.GAE%40google.com.



-- 
Ⲡⲟⲓⲙⲏⲛ Ⲅⲉⲱⲣⲅⲓⲟⲥ - Pimyn Girgis
Software Engineer
Kernel Dynamic Analysis
[email protected]