[syzbot] [bpf?] WARNING in do_check (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f83ec76bf285 Linux 6.17-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11d1947c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4d8792ecb6308d0f
dashboard link: https://syzkaller.appspot.com/bug?extid=e1fa4a4a9361f2f3bbd6
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1355f934580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12170e42580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f8eff1302251/disk-f83ec76b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1009d8f3246e/vmlinux-f83ec76b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5ba227871658/bzImage-f83ec76b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e1fa4a...@syzkaller.appspotmail.com

------------[ cut here ]------------
verifier bug: scc exit: no visit info for call chain (1)(1)
WARNING: CPU: 0 PID: 6062 at kernel/bpf/verifier.c:1950 maybe_exit_scc kernel/bpf/verifier.c:1949 [inline]
WARNING: CPU: 0 PID: 6062 at kernel/bpf/verifier.c:1950 update_branch_counts kernel/bpf/verifier.c:2040 [inline]
WARNING: CPU: 0 PID: 6062 at kernel/bpf/verifier.c:1950 do_check+0xe228/0xe520 kernel/bpf/verifier.c:20135
Modules linked in:
CPU: 0 UID: 0 PID: 6062 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:maybe_exit_scc kernel/bpf/verifier.c:1949 [inline]
RIP: 0010:update_branch_counts kernel/bpf/verifier.c:2040 [inline]
RIP: 0010:do_check+0xe228/0xe520 kernel/bpf/verifier.c:20135
Code: c6 05 35 d3 b6 0d 01 90 48 8b 7c 24 10 48 8b b4 24 e0 00 00 00 e8 28 8e 00 00 48 c7 c7 80 f6 91 8b 48 89 c6 e8 a9 a1 ac ff 90 <0f> 0b 90 90 e9 a8 fc ff ff e8 9a 04 e9 ff c6 05 c1 d2 b6 0d 01 90
RSP: 0018:ffffc90003b9f1c0 EFLAGS: 00010246
RAX: bb0e1817e9dd7600 RBX: 0000000000000000 RCX: ffff88802faf0000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc90003b9f528 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfa22c R12: dffffc0000000000
R13: ffffc90000a7e0a0 R14: 0000000000000000 R15: ffff88805b1ebd00
FS: 00005555720d8500(0000) GS:ffff888125c15000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000003000 CR3: 0000000075b7d000 CR4: 0000000000350ef0
Call Trace:
<TASK>
do_check_common+0x1949/0x24f0 kernel/bpf/verifier.c:23264
do_check_main kernel/bpf/verifier.c:23347 [inline]
bpf_check+0x1746a/0x1d2d0 kernel/bpf/verifier.c:24707
bpf_prog_load+0x1318/0x1930 kernel/bpf/syscall.c:2979
__sys_bpf+0x528/0x870 kernel/bpf/syscall.c:6029
__do_sys_bpf kernel/bpf/syscall.c:6139 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6137 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6137
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff4c0d8eba9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffeb05e37d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007ff4c0fd5fa0 RCX: 00007ff4c0d8eba9
RDX: 0000000000000048 RSI: 00002000000017c0 RDI: 0000000000000005
RBP: 00007ff4c0e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff4c0fd5fa0 R14: 00007ff4c0fd5fa0 R15: 0000000000000003
</TASK>


---
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[syzbot]

syzbot has bisected this issue to:

commit dadb59104c6441f54d0c42bba3e4bd11e25fc6d9
Author: Luis Gerhorst <luis.g...@fau.de>
Date: Sat Jul 5 19:09:07 2025 +0000

bpf: Fix aux usage after do_check_insn()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13850534580000
start commit: f83ec76bf285 Linux 6.17-rc6
git tree: upstream
final oops: https://syzkaller.appspot.com/x/report.txt?x=10450534580000
console output: https://syzkaller.appspot.com/x/log.txt?x=17850534580000

kernel config: https://syzkaller.appspot.com/x/.config?x=4d8792ecb6308d0f
dashboard link: https://syzkaller.appspot.com/bug?extid=e1fa4a4a9361f2f3bbd6

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1355f934580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12170e42580000

Reported-by: syzbot+e1fa4a...@syzkaller.appspotmail.com
Fixes: dadb59104c64 ("bpf: Fix aux usage after do_check_insn()")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection