syzbot


general protection fault in nft_fib6_eval

Status: closed as invalid on 2025/08/01 11:34
Subsystems: netfilter
[Documentation on labels]
First crash: 68d, last: 65d

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 10789 Comm: syz.0.1609 Not tainted 6.16.0-rc1-syzkaller-00239-g08215f5486ec #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:nft_fib6_eval+0x838/0xd70 net/ipv6/netfilter/nft_fib_ipv6.c:206
Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 19 05 00 00 48 8b ab d8 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 ea 04 00 00 48 8b 6d 00 4d 85 ff 74 5f e8 f0 d8
RSP: 0018:ffffc90003a271e8 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff8880799d63c0 RCX: ffffc90004e62000
RDX: 0000000000000000 RSI: ffffffff8a4642ae RDI: ffff8880799d6498
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000001000
R13: ffffc90003a27268 R14: ffffc90003a27649 R15: 0000000000000000
FS:  00007f5a89b416c0(0000) GS:ffff888124853000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f117ff8 CR3: 000000005ed38000 CR4: 00000000003526f0
DR0: 0000000000000040 DR1: 0000000000000004 DR2: 0000000000000003
DR3: 00000000000010e3 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 nft_fib_inet_eval+0x19a/0x230 net/netfilter/nft_fib_inet.c:34
 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
 nft_do_chain+0x2e6/0x1920 net/netfilter/nf_tables_core.c:285
 nft_do_chain_inet+0x18a/0x340 net/netfilter/nft_chain_filter.c:161
 nf_hook_entry_hookfn include/linux/netfilter.h:157 [inline]
 nf_hook_slow+0xbb/0x200 net/netfilter/core.c:623
 nf_hook.constprop.0+0x422/0x750 include/linux/netfilter.h:272
 NF_HOOK include/linux/netfilter.h:315 [inline]
 ip6_input+0xe0/0x2f0 net/ipv6/ip6_input.c:491
 dst_input include/net/dst.h:469 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
 NF_HOOK include/linux/netfilter.h:317 [inline]
 NF_HOOK include/linux/netfilter.h:311 [inline]
 ipv6_rcv+0x265/0x680 net/ipv6/ip6_input.c:309
 __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5977
 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6090
 netif_receive_skb_internal net/core/dev.c:6176 [inline]
 netif_receive_skb+0x137/0x7b0 net/core/dev.c:6235
 tun_rx_batched.isra.0+0x3ee/0x740 drivers/net/tun.c:1509
 tun_get_user+0x28a2/0x3b80 drivers/net/tun.c:1938
 tun_chr_write_iter+0xdc/0x210 drivers/net/tun.c:1984
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x6c4/0x1150 fs/read_write.c:686
 ksys_write+0x12a/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5a88d8d3df
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007f5a89b41000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f5a88fb5fa0 RCX: 00007f5a88d8d3df
RDX: 000000000000004e RSI: 0000200000000780 RDI: 00000000000000c8
RBP: 00007f5a88e10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000004e R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5a88fb5fa0 R15: 00007fff2055f538
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:nft_fib6_eval+0x838/0xd70 net/ipv6/netfilter/nft_fib_ipv6.c:206
Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 19 05 00 00 48 8b ab d8 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 ea 04 00 00 48 8b 6d 00 4d 85 ff 74 5f e8 f0 d8
RSP: 0018:ffffc90003a271e8 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff8880799d63c0 RCX: ffffc90004e62000
RDX: 0000000000000000 RSI: ffffffff8a4642ae RDI: ffff8880799d6498
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000001000
R13: ffffc90003a27268 R14: ffffc90003a27649 R15: 0000000000000000
FS:  00007f5a89b416c0(0000) GS:ffff888124853000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f117ff8 CR3: 000000005ed38000 CR4: 00000000003526f0
DR0: 0000000000000040 DR1: 0000000000000004 DR2: 0000000000000003
DR3: 00000000000010e3 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	df 48 89             	fisttps -0x77(%rax)
   3:	fa                   	cli
   4:	48 c1 ea 03          	shr    $0x3,%rdx
   8:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   c:	0f 85 19 05 00 00    	jne    0x52b
  12:	48 8b ab d8 00 00 00 	mov    0xd8(%rbx),%rbp
  19:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  20:	fc ff df
  23:	48 89 ea             	mov    %rbp,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2e:	0f 85 ea 04 00 00    	jne    0x51e
  34:	48 8b 6d 00          	mov    0x0(%rbp),%rbp
  38:	4d 85 ff             	test   %r15,%r15
  3b:	74 5f                	je     0x9c
  3d:	e8                   	.byte 0xe8
  3e:	f0                   	lock
  3f:	d8                   	.byte 0xd8

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/15 20:34 upstream 08215f5486ec 5f4b362d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root general protection fault in nft_fib6_eval
2025/06/13 02:44 upstream 27605c8c0f69 98683f8f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 general protection fault in nft_fib6_eval
* Struck through repros no longer work on HEAD.