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AKwUvBx/9YuGb3nwjdDp1aui6fkHdrN+OP3hhiOlQHriUyZFzVkWfNP0EPZka86i61XGu2I5fkA=@vger.kernel.org X-Gm-Message-State: AFuF++l839eXAty6MkJO3ZWuAxYXPViB3SKZFhP5DaD91J/0nHIHBqZX aYe1pywY02Q8R8wM/NaKan2IEv97Oq2yji0vk2CwUYsUV4NZXkOdsu9d6t7afJiDH3K036Q6QqP lsWkSs4WImVzpscNQysOUJriv3eqNCaOaCDX9MykfpIZOfezDNvIv99wViUA= Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:214:b0:6b3:61fa:102 with SMTP id 006d021491bc7-6b6fdfc2b9bmr4233842eaf.34.1788531276739; Fri, 04 Sep 2026 07:14:36 -0700 (PDT) Date: Fri, 04 Sep 2026 07:14:36 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a9ad24c.b5d4176b.238c3e.0001.GAE@google.com> Subject: [syzbot] [bpf?] WARNING in bpf_mark_chain_precision From: syzbot To: andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, emil@etsalapatis.com, ihor.solodrai@linux.dev, jolsa@kernel.org, linux-kernel@vger.kernel.org, martin.lau@linux.dev, memxor@gmail.com, netdev@vger.kernel.org, song@kernel.org, syzkaller-bugs@googlegroups.com, yonghong.song@linux.dev Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: e044668419b9 Merge branch 'misc-bug-fixes-part-1' git tree: bpf console+strace: https://syzkaller.appspot.com/x/log.txt?x=162038f9580000 kernel config: https://syzkaller.appspot.com/x/.config?x=13dd96f4206498c4 dashboard link: https://syzkaller.appspot.com/bug?extid=7b47f87674e9a1569110 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=165fcb49580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=112038f9580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/2c0c9fa35baf/disk-e0446684.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/1ed2d74549a1/vmlinux-e0446684.xz kernel image: https://storage.googleapis.com/syzbot-assets/479e5164ed3b/bzImage-e0446684.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+7b47f87674e9a1569110@syzkaller.appspotmail.com ------------[ cut here ]------------ verifier bug: backtracking misuse WARNING: kernel/bpf/backtrack.c:829 at bpf_mark_chain_precision+0x571b/0x76b0 kernel/bpf/backtrack.c:829, CPU#1: syz-executor403/5624 Modules linked in: CPU: 1 UID: 0 PID: 5624 Comm: syz-executor403 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:bpf_mark_chain_precision+0x571b/0x76b0 kernel/bpf/backtrack.c:829 Code: ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 16 ff ff ff 48 89 df e8 76 17 44 00 e9 09 ff ff ff e8 0c d0 d4 ff 48 8d 3d b5 50 6a 0e <67> 48 0f b9 3a 48 8b 3c 24 48 81 c7 88 08 00 00 48 c7 c6 a0 c6 f6 RSP: 0018:ffffc90003957228 EFLAGS: 00010293 RAX: ffffffff81f23d54 RBX: 0000000000000001 RCX: ffff88807f7b9f40 RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffffffff905c8e10 RBP: 0000000000000003 R08: ffff88807f7b9f40 R09: 0000000000000003 R10: 0000000000000007 R11: 0000000000000000 R12: ffff88807f4f3050 R13: dffffc0000000000 R14: 0000000000000001 R15: 0000000000000000 FS: 00005555805e0400(0000) GS:ffff888125024000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000006a9ee0 CR3: 000000007133a000 CR4: 00000000003526f0 Call Trace: mark_chain_precision kernel/bpf/verifier.c:3373 [inline] check_helper_call kernel/bpf/verifier.c:10894 [inline] do_check_insn+0x12a74/0x17c20 kernel/bpf/verifier.c:18177 do_check kernel/bpf/verifier.c:18363 [inline] do_check_common+0x3c19/0x5d30 kernel/bpf/verifier.c:19444 do_check_main kernel/bpf/verifier.c:19540 [inline] bpf_check+0x2639/0x2e10 kernel/bpf/verifier.c:21195 bpf_prog_load+0x14d6/0x1c20 kernel/bpf/syscall.c:3133 __sys_bpf+0xd0d/0xd90 kernel/bpf/syscall.c:6367 __do_sys_bpf kernel/bpf/syscall.c:6486 [inline] __se_sys_bpf kernel/bpf/syscall.c:6483 [inline] __x64_sys_bpf+0xba/0xd0 kernel/bpf/syscall.c:6483 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f4f25cf1749 Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff991a6f18 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4f25cf1749 RDX: 0000000000000080 RSI: 0000200000000300 RDI: 0000000000000005 RBP: 0000000000000000 R08: 0000000000000006 R09: 0000000000000006 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f4f25d84c40 R15: 0000000000000002 ---------------- Code disassembly (best guess): 0: ff 89 d9 80 e1 07 decl 0x7e180d9(%rcx) 6: 80 c1 03 add $0x3,%cl 9: 38 c1 cmp %al,%cl b: 0f 8c 16 ff ff ff jl 0xffffff27 11: 48 89 df mov %rbx,%rdi 14: e8 76 17 44 00 call 0x44178f 19: e9 09 ff ff ff jmp 0xffffff27 1e: e8 0c d0 d4 ff call 0xffd4d02f 23: 48 8d 3d b5 50 6a 0e lea 0xe6a50b5(%rip),%rdi # 0xe6a50df * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: 48 8b 3c 24 mov (%rsp),%rdi 33: 48 81 c7 88 08 00 00 add $0x888,%rdi 3a: 48 rex.W 3b: c7 .byte 0xc7 3c: c6 (bad) 3d: a0 .byte 0xa0 3e: c6 (bad) 3f: f6 .byte 0xf6 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup