syzbot


general protection fault in rt6_find_cached_rt

Status: upstream: reported on 2025/05/04 16:41
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+c98f63d3185beafbc080@syzkaller.appspotmail.com
First crash: 14d, last: 14d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [net?] general protection fault in rt6_find_cached_rt 0 (1) 2025/05/04 16:41

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
CPU: 1 UID: 0 PID: 5881 Comm: kworker/1:4 Not tainted 6.15.0-rc4-syzkaller-00189-g2bfcee565c3a #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Workqueue: mld mld_ifc_work
RIP: 0010:fib6_nh_get_excptn_bucket net/ipv6/route.c:1662 [inline]
RIP: 0010:rt6_find_cached_rt+0xb9/0x270 net/ipv6/route.c:1858
Code: 48 c1 e8 03 48 89 44 24 08 48 8b 44 24 08 80 3c 18 00 74 08 4c 89 f7 e8 65 8c 14 f8 49 8b 2e 48 83 c5 60 48 89 e8 48 c1 e8 03 <80> 3c 18 00 74 08 48 89 ef e8 49 8c 14 f8 4c 8b 6d 00 e8 70 c5 48
RSP: 0018:ffffc90000a084e0 EFLAGS: 00010206
RAX: 000000000000000c RBX: dffffc0000000000 RCX: 0000000000000100
RDX: ffff88807f319e00 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000060 R08: ffff88807ef99633 R09: 1ffff1100fdf32c6
R10: dffffc0000000000 R11: ffffed100fdf32c7 R12: ffffc90000a085b8
R13: 0000000000000000 R14: ffffc90000a085b0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881261cc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbb92ae56c0 CR3: 000000006a5c2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000005325
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 ip6_pol_route+0x28d/0x1180 net/ipv6/route.c:2273
 pol_lookup_func include/net/ip6_fib.h:616 [inline]
 fib6_rule_lookup+0x55e/0x6f0 net/ipv6/fib6_rules.c:125
 ip6_route_input_lookup net/ipv6/route.c:2335 [inline]
 ip6_route_input+0x6ce/0xa50 net/ipv6/route.c:2631
 ip6_rcv_finish+0x141/0x2d0 net/ipv6/ip6_input.c:77
 NF_HOOK+0x309/0x3a0 include/linux/netfilter.h:314
 __netif_receive_skb_one_core net/core/dev.c:5887 [inline]
 __netif_receive_skb+0xd3/0x380 net/core/dev.c:6000
 process_backlog+0x60e/0x14f0 net/core/dev.c:6352
 __napi_poll+0xc4/0x480 net/core/dev.c:7324
 napi_poll net/core/dev.c:7388 [inline]
 net_rx_action+0x6ea/0xdf0 net/core/dev.c:7510
 handle_softirqs+0x283/0x870 kernel/softirq.c:579
 do_softirq+0xec/0x180 kernel/softirq.c:480
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x17d/0x1c0 kernel/softirq.c:407
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:910 [inline]
 __dev_queue_xmit+0x1cd7/0x3a70 net/core/dev.c:4656
 neigh_output include/net/neighbour.h:539 [inline]
 ip6_finish_output2+0x11fb/0x16a0 net/ipv6/ip6_output.c:141
 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline]
 ip6_finish_output+0x234/0x7d0 net/ipv6/ip6_output.c:226
 NF_HOOK+0x9e/0x380 include/linux/netfilter.h:314
 mld_sendpack+0x800/0xd80 net/ipv6/mcast.c:1868
 mld_send_cr net/ipv6/mcast.c:2169 [inline]
 mld_ifc_work+0x835/0xde0 net/ipv6/mcast.c:2702
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xadb/0x17a0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:fib6_nh_get_excptn_bucket net/ipv6/route.c:1662 [inline]
RIP: 0010:rt6_find_cached_rt+0xb9/0x270 net/ipv6/route.c:1858
Code: 48 c1 e8 03 48 89 44 24 08 48 8b 44 24 08 80 3c 18 00 74 08 4c 89 f7 e8 65 8c 14 f8 49 8b 2e 48 83 c5 60 48 89 e8 48 c1 e8 03 <80> 3c 18 00 74 08 48 89 ef e8 49 8c 14 f8 4c 8b 6d 00 e8 70 c5 48
RSP: 0018:ffffc90000a084e0 EFLAGS: 00010206

RAX: 000000000000000c RBX: dffffc0000000000 RCX: 0000000000000100
RDX: ffff88807f319e00 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000060 R08: ffff88807ef99633 R09: 1ffff1100fdf32c6
R10: dffffc0000000000 R11: ffffed100fdf32c7 R12: ffffc90000a085b8
R13: 0000000000000000 R14: ffffc90000a085b0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881261cc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbb92ae56c0 CR3: 000000006a5c2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000005325
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	48 c1 e8 03          	shr    $0x3,%rax
   4:	48 89 44 24 08       	mov    %rax,0x8(%rsp)
   9:	48 8b 44 24 08       	mov    0x8(%rsp),%rax
   e:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1)
  12:	74 08                	je     0x1c
  14:	4c 89 f7             	mov    %r14,%rdi
  17:	e8 65 8c 14 f8       	call   0xf8148c81
  1c:	49 8b 2e             	mov    (%r14),%rbp
  1f:	48 83 c5 60          	add    $0x60,%rbp
  23:	48 89 e8             	mov    %rbp,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	48 89 ef             	mov    %rbp,%rdi
  33:	e8 49 8c 14 f8       	call   0xf8148c81
  38:	4c 8b 6d 00          	mov    0x0(%rbp),%r13
  3c:	e8                   	.byte 0xe8
  3d:	70 c5                	jo     0x4
  3f:	48                   	rex.W

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/02 23:16 upstream 2bfcee565c3a b0714e37 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in rt6_find_cached_rt
* Struck through repros no longer work on HEAD.