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Sun, 8 Jun 2025 16:00:55 +0200 (CEST) From: Charalampos Mitrodimas To: syzbot Cc: andrii@kernel.org, davem@davemloft.net, edumazet@google.com, horms@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com, tj@kernel.org, yangfeng@kylinos.cn Subject: Re: [syzbot] [net?] WARNING: suspicious RCU usage in task_cls_state In-Reply-To: <683428c7.a70a0220.29d4a0.0800.GAE@google.com> References: <683428c7.a70a0220.29d4a0.0800.GAE@google.com> Date: Sun, 08 Jun 2025 14:00:38 +0000 Message-ID: <87frgafi49.fsf@posteo.net> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain syzbot writes: > Hello, > > syzbot found the following issue on: > > HEAD commit: 079e5c56a5c4 bpf: Fix error return value in bpf_copy_from_.. > git tree: bpf-next > console+strace: https://syzkaller.appspot.com/x/log.txt?x=178ae170580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=c6c517d2f439239 > dashboard link: https://syzkaller.appspot.com/bug?extid=b4169a1cfb945d2ed0ec > compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13bc35f4580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15f195f4580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/8d7d35d067bc/disk-079e5c56.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/74d2648ea7f4/vmlinux-079e5c56.xz > kernel image: https://storage.googleapis.com/syzbot-assets/e751e253ee4f/bzImage-079e5c56.xz > > The issue was bisected to: > > commit ee971630f20fd421fffcdc4543731ebcb54ed6d0 > Author: Feng Yang > Date: Tue May 6 06:14:33 2025 +0000 > > bpf: Allow some trace helpers for all prog types > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14cd68e8580000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=16cd68e8580000 > console output: https://syzkaller.appspot.com/x/log.txt?x=12cd68e8580000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+b4169a1cfb945d2ed0ec@syzkaller.appspotmail.com > Fixes: ee971630f20f ("bpf: Allow some trace helpers for all prog types") > > ============================= > WARNING: suspicious RCU usage > 6.15.0-rc4-syzkaller-g079e5c56a5c4 #0 Not tainted > ----------------------------- > net/core/netclassid_cgroup.c:24 suspicious rcu_dereference_check() usage! > > other info that might help us debug this: > > > rcu_scheduler_active = 2, debug_locks = 1 > 1 lock held by syz-executor296/5833: > #0: ffffffff8df3ba40 (rcu_read_lock_trace){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] > #0: ffffffff8df3ba40 (rcu_read_lock_trace){....}-{0:0}, at: rcu_read_lock_trace+0x38/0x80 include/linux/rcupdate_trace.h:58 > > stack backtrace: > CPU: 0 UID: 0 PID: 5833 Comm: syz-executor296 Not tainted 6.15.0-rc4-syzkaller-g079e5c56a5c4 #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 > Call Trace: > > dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 > lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6865 > task_cls_state+0x1a5/0x1d0 net/core/netclassid_cgroup.c:23 > __task_get_classid include/net/cls_cgroup.h:50 [inline] > ____bpf_get_cgroup_classid_curr net/core/filter.c:3086 [inline] > bpf_get_cgroup_classid_curr+0x18/0x60 net/core/filter.c:3084 > bpf_prog_83da9cb0e78d4768+0x2c/0x5a > bpf_dispatcher_nop_func include/linux/bpf.h:1322 [inline] > __bpf_prog_run include/linux/filter.h:718 [inline] > bpf_prog_run include/linux/filter.h:725 [inline] > bpf_prog_run_pin_on_cpu+0x67/0x150 include/linux/filter.h:742 > bpf_prog_test_run_syscall+0x312/0x4b0 net/bpf/test_run.c:1564 > bpf_prog_test_run+0x2a9/0x340 kernel/bpf/syscall.c:4429 > __sys_bpf+0x4a4/0x860 kernel/bpf/syscall.c:5854 > __do_sys_bpf kernel/bpf/syscall.c:5943 [inline] > __se_sys_bpf kernel/bpf/syscall.c:5941 [inline] > __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5941 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7fda75b18a69 > Code: d8 5b 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 b8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007ffdd0546d48 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fda75b18a69 > RDX: 0000000000000048 RSI: 0000200000000500 RDI: 000000000000000a > > > --- > 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. > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > > 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. #syz test: https://github.com/charmitro/linux.git e5c42d49bfb967c3c35f536971f397492d2f46bf