WARNING in ip_rt_bug (2)

Status: upstream: reported on 2026/08/26 03:11
Reported-by: syzbot+2e7e9cdec37f1af29ba3@syzkaller.appspotmail.com
First crash: 17h27m, last: 17h27m
Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 WARNING in ip_rt_bug -1 syz, C error 2 1788d 2336d 0/1 upstream: reported C repro on 2020/04/03 11:53
linux-4.14 WARNING in ip_rt_bug -1 syz, C inconclusive 1 2264d 2324d 0/1 upstream: reported C repro on 2020/04/15 03:43
linux-6.1 WARNING in ip_rt_bug (2) -1 1 874d 874d 0/3 auto-obsoleted due to no activity on 2024/07/13 04:22
linux-6.1 WARNING in ip_rt_bug -1 1 1105d 1105d 0/3 auto-obsoleted due to no activity on 2023/11/25 06:32
upstream WARNING in ip_rt_bug (2) net -1 syz, C done error 612 112d 1414d 29/29 fixed on 2026/05/06 16:40
linux-5.15 WARNING in ip_rt_bug -1 7 478d 597d 0/3 auto-obsoleted due to no activity on 2025/08/13 17:11
linux-6.6 WARNING in ip_rt_bug -1 1 244d 244d 0/2 auto-obsoleted due to no activity on 2026/04/04 15:30
upstream WARNING in ip_rt_bug (3) prio:high net -1 syz, C error 54 88d 99d 29/29 fixed on 2026/07/15 08:27
upstream WARNING in ip_rt_bug net -1 1 3069d 3061d 0/29 auto-closed as invalid on 2019/02/22 10:34
linux-6.1 WARNING in ip_rt_bug (4) origin:lts-only -1 syz, C inconclusive 5 144d 352d 0/3 upstream: reported C repro on 2025/09/08 02:20
linux-6.1 WARNING in ip_rt_bug (3) -1 26 446d 613d 0/3 auto-obsoleted due to no activity on 2025/09/07 04:48

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 5525 at net/ipv4/route.c:1319 kfree_skb include/linux/skbuff.h:1118 [inline]
WARNING: CPU: 0 PID: 5525 at net/ipv4/route.c:1319 ip_rt_bug+0x22/0xf0 net/ipv4/route.c:1318
Modules linked in:
CPU: 0 PID: 5525 Comm: syz.4.443 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:ip_rt_bug+0x22/0xf0 net/ipv4/route.c:1319
Code: 5a f9 e9 41 ff ff ff 90 41 57 41 56 41 55 41 54 53 48 89 d3 e8 1f 86 15 f9 66 90 e8 18 86 15 f9 48 89 df 31 f6 e8 8e 51 7c ff <0f> 0b 31 c0 5b 41 5c 41 5d 41 5e 41 5f c3 49 bd 00 00 00 00 00 fc
RSP: 0018:ffffc900032a6d98 EFLAGS: 00010286
RAX: 4d13cbcd42628f00 RBX: ffff88802499a3c0 RCX: 4d13cbcd42628f00
RDX: dffffc0000000000 RSI: ffffffff8a7a42a0 RDI: ffffffff8a7a4260
RBP: ffff88802a9e2500 R08: ffffffff901ef167 R09: 1ffffffff203de2c
R10: dffffc0000000000 R11: fffffbfff203de2d R12: ffff88802a9e2530
R13: ffff88802499a418 R14: ffff88802499a3c0 R15: ffff88801beead80
FS:  00007f57a66236c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32c1eff8 CR3: 0000000073e64000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 dst_output include/net/dst.h:452 [inline]
 ip_local_out net/ipv4/ip_output.c:126 [inline]
 ip_send_skb+0x12b/0x1d0 net/ipv4/ip_output.c:1590
 __icmp_send+0xd68/0x1140 net/ipv4/icmp.c:794
 icmp_send include/net/icmp.h:43 [inline]
 nf_send_unreach+0x5f1/0x7a0 net/ipv4/netfilter/nf_reject_ipv4.c:-1
 nft_reject_inet_eval+0x4b3/0x680 net/netfilter/nft_reject_inet.c:27
 expr_call_ops_eval net/netfilter/nf_tables_core.c:198 [inline]
 nft_do_chain+0x491/0x14d0 net/netfilter/nf_tables_core.c:238
 nft_do_chain_inet+0x25c/0x340 net/netfilter/nft_chain_filter.c:161
 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
 nf_hook_slow+0xb9/0x200 net/netfilter/core.c:584
 nf_hook include/linux/netfilter.h:257 [inline]
 NF_HOOK+0x1f2/0x390 include/linux/netfilter.h:300
 __netif_receive_skb_one_core net/core/dev.c:5551 [inline]
 __netif_receive_skb+0xcc/0x290 net/core/dev.c:5665
 netif_receive_skb_internal net/core/dev.c:5751 [inline]
 netif_receive_skb+0x19e/0x700 net/core/dev.c:5810
 tun_rx_batched+0x606/0x760 drivers/net/tun.c:-1
 tun_get_user+0x25bf/0x3b60 drivers/net/tun.c:1989
 tun_chr_write_iter+0x112/0x1e0 drivers/net/tun.c:2019
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f57a838b90e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f57a6622fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f57a66236c0 RCX: 00007f57a838b90e
RDX: 0000000000000086 RSI: 0000200000000280 RDI: 00000000000000c8
RBP: 00007f57a8462024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f57a8653038 R14: 00007f57a8652fa0 R15: 00007ffc77b36e68
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/26 03:10 linux-5.15.y 945fa863f02c 6a91adb4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in ip_rt_bug
* Struck through repros no longer work on HEAD.