Re: [syzbot] [bpf?] [net?] WARNING in bpf_lwt_seg6_adjust_srh

On 2024-06-25 09:51:25 [-0700], syzbot wrote:

Hello,

Hi,

…

commit d1542d4ae4dfdc47c9b3205ebe849ed23af213dd
Author: Sebastian Andrzej Siewior [off-list ref]
Date:   Thu Jun 20 13:22:02 2024 +0000

    seg6: Use nested-BH locking for seg6_bpf_srh_states.

…

WARNING: CPU: 0 PID: 5091 at net/core/filter.c:6579 ____bpf_lwt_seg6_adjust_srh net/core/filter.c:6579 [inline]
WARNING: CPU: 0 PID: 5091 at net/core/filter.c:6579 bpf_lwt_seg6_adjust_srh+0x877/0xb30 net/core/filter.c:6568

…

Call Trace:
 <TASK>
 bpf_prog_2088341bddeddc1d+0x40/0x42
 bpf_dispatcher_nop_func include/linux/bpf.h:1243 [inline]
 __bpf_prog_run include/linux/filter.h:691 [inline]
 bpf_prog_run include/linux/filter.h:698 [inline]
 bpf_test_run+0x4f0/0xa90 net/bpf/test_run.c:432
 bpf_prog_test_run_skb+0xafa/0x13b0 net/bpf/test_run.c:1081
 bpf_prog_test_run+0x33a/0x3b0 kernel/bpf/syscall.c:4313
 __sys_bpf+0x48d/0x810 kernel/bpf/syscall.c:5728
 __do_sys_bpf kernel/bpf/syscall.c:5817 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5815 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5815
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

I assumed this can only originate from input_action_end_bpf() but
clearly this not a hard requirement based on the report.
So this a valid invocation and it should not have been killer earlier in
the stack?

Sebastian