syzbot


WARNING in dst_release

Status: upstream: reported on 2026/04/01 22:09
Reported-by: syzbot+3d1454ccef42e43b13f8@syzkaller.appspotmail.com
First crash: 112d, last: 19d
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in dst_release net -1 syz done 2 1982d 1981d 20/29 fixed on 2021/04/09 19:46
upstream WARNING in dst_release (2) net -1 syz error done 30 1686d 1908d 0/29 closed as invalid on 2021/12/14 10:52
upstream WARNING in dst_release (3) net -1 3 1601d 1681d 20/29 fixed on 2022/03/08 16:11

Sample crash report:
------------[ cut here ]------------
dst_release underflow
WARNING: CPU: 0 PID: 24405 at net/core/dst.c:172 dst_release+0x15a/0x180 net/core/dst.c:172
Modules linked in:
CPU: 0 PID: 24405 Comm: syz.2.9262 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:dst_release+0x15a/0x180 net/core/dst.c:172
Code: 8b 48 89 da 44 89 f1 5b 41 5e 41 5f 5d e9 7e e2 ca 01 e8 e9 62 8f f9 c6 05 ec a7 8d 05 01 48 c7 c7 e0 54 1f 8b e8 06 9a ca 01 <0f> 0b e9 0b ff ff ff 44 89 f1 80 e1 07 fe c1 38 c1 0f 8c 41 ff ff
RSP: 0018:ffffc90003376fd8 EFLAGS: 00010246
RAX: 4cb9e5b0a82e7c00 RBX: ffff8880791d7000 RCX: 0000000000080000
RDX: ffffc90005daa000 RSI: 0000000000009b11 RDI: 0000000000009b12
RBP: ffffc90003377130 R08: ffff8880b902795b R09: 1ffff11017204f2b
R10: dffffc0000000000 R11: ffffed1017204f2c R12: dffffc0000000000
R13: ffffc90003377098 R14: 00000000ffffffff R15: ffff8880570c5140
FS:  00007f34d82386c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001342 CR3: 000000004b1e6000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ip6_redirect_no_header+0x232/0x2c0 net/ipv6/route.c:3174
 ndisc_redirect_rcv+0x3a8/0x5e0 net/ipv6/ndisc.c:1580
 ndisc_rcv+0x383/0x4e0 net/ipv6/ndisc.c:1804
 icmpv6_rcv+0xe5b/0x1620 net/ipv6/icmp.c:970
 ip6_protocol_deliver_rcu+0x97b/0x1360 net/ipv6/ip6_input.c:425
 ip6_input_finish+0xa2/0x130 net/ipv6/ip6_input.c:466
 NF_HOOK+0x303/0x390 include/linux/netfilter.h:302
 ip6_input net/ipv6/ip6_input.c:475 [inline]
 ip6_mc_input+0x79f/0xbc0 net/ipv6/ip6_input.c:569
 NF_HOOK+0x303/0x390 include/linux/netfilter.h:302
 __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/0x3b40 drivers/net/tun.c:1989
 tun_chr_write_iter+0x112/0x1e0 drivers/net/tun.c:2019
 call_write_iter include/linux/fs.h:2173 [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: 0033:0x7f34d9fa068e
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:00007f34d8237fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f34d82386c0 RCX: 00007f34d9fa068e
RDX: 000000000000005e RSI: 0000200000001340 RDI: 00000000000000c8
RBP: 00007f34da075e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f34da268038 R14: 00007f34da267fa0 R15: 00007fffed11fd18
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/03 21:15 linux-5.15.y eceeec79dbc6 fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in dst_release
2026/04/01 22:08 linux-5.15.y 91d48252ad4b 0cb124d5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in dst_release
* Struck through repros no longer work on HEAD.