WARNING in __mark_chain_precision

Status: upstream: reported C repro on 2026/09/04 07:46
Reported-by: syzbot+36ee5673bcd908500165@syzkaller.appspotmail.com
First crash: 3d15h, last: 1d19h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in __mark_chain_precision (4) bpf -1 syz, C 8 869d 889d 25/29 fixed on 2024/06/05 13:52
upstream WARNING in __mark_chain_precision (2) bpf -1 syz, C done 18 2548d 2566d 13/29 fixed on 2019/10/09 10:54
upstream WARNING in __mark_chain_precision (3) bpf -1 syz, C done 19 980d 1002d 25/29 fixed on 2024/01/31 06:43
upstream WARNING in __mark_chain_precision -1 syz, C done 105 2582d 2618d 12/29 fixed on 2019/08/14 02:14

Sample crash report:
------------[ cut here ]------------
backtracing misuse
WARNING: CPU: 1 PID: 5935 at kernel/bpf/verifier.c:4381 __mark_chain_precision+0x59c2/0x60f0 kernel/bpf/verifier.c:4381
Modules linked in:
CPU: 1 PID: 5935 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__mark_chain_precision+0x59c2/0x60f0 kernel/bpf/verifier.c:4381
Code: 8c 07 ff ff ff 4c 89 ff e8 2b f7 47 00 e9 fa fe ff ff e8 61 75 ef ff c6 05 b1 02 df 0c 01 48 c7 c7 60 a6 d0 8a e8 0e 42 b9 ff <0f> 0b b8 f2 ff ff ff e9 25 f4 ff ff e8 3d 75 ef ff e9 19 f4 ff ff
RSP: 0018:ffffc90003396d00 EFLAGS: 00010246
RAX: 1c8cb6c335114900 RBX: 0000000000000006 RCX: ffff888077939e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc90003396ef0 R08: ffff8880b8f28c53 R09: 1ffff110171e518a
R10: dffffc0000000000 R11: ffffed10171e518b R12: 0000000000000001
R13: dffffc0000000000 R14: ffff88807602b450 R15: 0000000000000001
FS:  0000555581373500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4da2a70050 CR3: 0000000076ff5000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 mark_chain_precision kernel/bpf/verifier.c:4536 [inline]
 check_helper_call+0x42d3/0x6340 kernel/bpf/verifier.c:10235
 do_check+0x87fb/0xd0a0 kernel/bpf/verifier.c:17478
 do_check_common+0xacc/0x1410 kernel/bpf/verifier.c:19903
 do_check_main kernel/bpf/verifier.c:19966 [inline]
 bpf_check+0x65d1/0xec30 kernel/bpf/verifier.c:20634
 bpf_prog_load+0x10fa/0x1610 kernel/bpf/syscall.c:2753
 __sys_bpf+0x5ba/0x890 kernel/bpf/syscall.c:5478
 __do_sys_bpf kernel/bpf/syscall.c:5582 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5580 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5580
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4da2b9e159
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:00007ffc292ec8e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f4da2e25fa0 RCX: 00007f4da2b9e159
RDX: 0000000000000080 RSI: 0000200000000300 RDI: 0000000000000005
RBP: 00007f4da2c35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4da2e25fac R14: 00007f4da2e25fa0 R15: 00007f4da2e25fa0
 </TASK>

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/04 21:28 linux-6.6.y 8b73de7da85f f65209a4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf WARNING in __mark_chain_precision
2026/09/04 07:45 linux-6.6.y 8b73de7da85f 801f0966 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf WARNING in __mark_chain_precision
2026/09/06 03:43 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf WARNING in __mark_chain_precision
2026/09/06 03:42 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf WARNING in __mark_chain_precision
2026/09/06 03:39 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf WARNING in __mark_chain_precision
2026/09/05 12:29 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf WARNING in __mark_chain_precision
2026/09/05 12:28 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf WARNING in __mark_chain_precision
2026/09/05 12:22 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf WARNING in __mark_chain_precision
* Struck through repros no longer work on HEAD.