====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.3.4/4389 is trying to acquire lock: ffff888073db5238 (&trie->lock){....}-{2:2}, at: trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467 but task is already holding lock: ffffffff8d1ca2a8 (depot_lock){-.-.}-{2:2}, at: __stack_depot_save+0x1e4/0x460 lib/stackdepot.c:479 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (depot_lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 __stack_depot_save+0x1e4/0x460 lib/stackdepot.c:479 kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x60/0x70 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:383 kasan_kmalloc include/linux/kasan.h:211 [inline] __do_kmalloc_node mm/slab_common.c:936 [inline] __kmalloc_node+0xb0/0x240 mm/slab_common.c:943 kmalloc_node include/linux/slab.h:589 [inline] bpf_map_kmalloc_node+0xb8/0x1a0 kernel/bpf/syscall.c:454 lpm_trie_node_alloc kernel/bpf/lpm_trie.c:291 [inline] trie_update_elem+0x160/0xe90 kernel/bpf/lpm_trie.c:338 bpf_map_update_value+0x59e/0x670 kernel/bpf/syscall.c:228 generic_map_update_batch+0x569/0x850 kernel/bpf/syscall.c:1709 bpf_map_do_batch+0x466/0x600 kernel/bpf/syscall.c:-1 __sys_bpf+0x65f/0x6d0 kernel/bpf/syscall.c:-1 __do_sys_bpf kernel/bpf/syscall.c:5131 [inline] __se_sys_bpf kernel/bpf/syscall.c:5129 [inline] __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5129 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #0 (&trie->lock){....}-{2:2}: check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain kernel/locking/lockdep.c:3825 [inline] __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467 bpf_prog_5186c38a4019a4cb+0x42/0x46 bpf_dispatcher_nop_func include/linux/bpf.h:1011 [inline] __bpf_prog_run include/linux/filter.h:603 [inline] bpf_prog_run include/linux/filter.h:610 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline] bpf_trace_run2+0x1cd/0x3b0 kernel/trace/bpf_trace.c:2324 trace_contention_end+0x13f/0x190 include/trace/events/lock.h:122 __pv_queued_spin_lock_slowpath+0x7e8/0x9c0 kernel/locking/qspinlock.c:560 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline] queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] _raw_spin_lock_irqsave+0xb0/0xf0 kernel/locking/spinlock.c:162 __stack_depot_save+0x1e4/0x460 lib/stackdepot.c:479 kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x60/0x70 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:383 kasan_kmalloc include/linux/kasan.h:211 [inline] __do_kmalloc_node mm/slab_common.c:936 [inline] __kmalloc_node_track_caller+0xae/0x230 mm/slab_common.c:956 kstrdup mm/util.c:61 [inline] kstrdup_const+0x56/0x90 mm/util.c:84 __kernfs_new_node+0x99/0x7d0 fs/kernfs/dir.c:610 kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:690 kernfs_create_dir_ns+0x40/0x120 fs/kernfs/dir.c:1046 sysfs_create_dir_ns+0x120/0x280 fs/sysfs/dir.c:59 create_dir lib/kobject.c:63 [inline] kobject_add_internal+0x6b8/0xc80 lib/kobject.c:231 kobject_add_varg lib/kobject.c:366 [inline] kobject_init_and_add+0x122/0x190 lib/kobject.c:449 rx_queue_add_kobject net/core/net-sysfs.c:1061 [inline] net_rx_queue_update_kobjects+0x1cd/0x4a0 net/core/net-sysfs.c:1112 register_queue_kobjects net/core/net-sysfs.c:1772 [inline] netdev_register_kobject+0x223/0x310 net/core/net-sysfs.c:2017 register_netdevice+0x12b9/0x1aa0 net/core/dev.c:10204 ppp_unit_register drivers/net/ppp/ppp_generic.c:1229 [inline] ppp_dev_configure+0x874/0xad0 drivers/net/ppp/ppp_generic.c:1285 ppp_create_interface drivers/net/ppp/ppp_generic.c:3362 [inline] ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1070 [inline] ppp_ioctl+0x65f/0x1940 drivers/net/ppp/ppp_generic.c:743 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(depot_lock); lock(&trie->lock); lock(depot_lock); lock(&trie->lock); *** DEADLOCK *** 4 locks held by syz.3.4/4389: #0: ffffffff8d5931e8 (ppp_mutex){+.+.}-{3:3}, at: ppp_ioctl+0xca/0x1940 drivers/net/ppp/ppp_generic.c:739 #1: ffffffff8dd42028 (rtnl_mutex){+.+.}-{3:3}, at: ppp_create_interface drivers/net/ppp/ppp_generic.c:3360 [inline] #1: ffffffff8dd42028 (rtnl_mutex){+.+.}-{3:3}, at: ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1070 [inline] #1: ffffffff8dd42028 (rtnl_mutex){+.+.}-{3:3}, at: ppp_ioctl+0x64f/0x1940 drivers/net/ppp/ppp_generic.c:743 #2: ffffffff8d1ca2a8 (depot_lock){-.-.}-{2:2}, at: __stack_depot_save+0x1e4/0x460 lib/stackdepot.c:479 #3: ffffffff8cb2a9e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #3: ffffffff8cb2a9e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #3: ffffffff8cb2a9e0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline] #3: ffffffff8cb2a9e0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xda/0x3b0 kernel/trace/bpf_trace.c:2324 stack backtrace: CPU: 1 PID: 4389 Comm: syz.3.4 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain kernel/locking/lockdep.c:3825 [inline] __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467 bpf_prog_5186c38a4019a4cb+0x42/0x46 bpf_dispatcher_nop_func include/linux/bpf.h:1011 [inline] __bpf_prog_run include/linux/filter.h:603 [inline] bpf_prog_run include/linux/filter.h:610 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline] bpf_trace_run2+0x1cd/0x3b0 kernel/trace/bpf_trace.c:2324 trace_contention_end+0x13f/0x190 include/trace/events/lock.h:122 __pv_queued_spin_lock_slowpath+0x7e8/0x9c0 kernel/locking/qspinlock.c:560 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline] queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] _raw_spin_lock_irqsave+0xb0/0xf0 kernel/locking/spinlock.c:162 __stack_depot_save+0x1e4/0x460 lib/stackdepot.c:479 kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x60/0x70 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:383 kasan_kmalloc include/linux/kasan.h:211 [inline] __do_kmalloc_node mm/slab_common.c:936 [inline] __kmalloc_node_track_caller+0xae/0x230 mm/slab_common.c:956 kstrdup mm/util.c:61 [inline] kstrdup_const+0x56/0x90 mm/util.c:84 __kernfs_new_node+0x99/0x7d0 fs/kernfs/dir.c:610 kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:690 kernfs_create_dir_ns+0x40/0x120 fs/kernfs/dir.c:1046 sysfs_create_dir_ns+0x120/0x280 fs/sysfs/dir.c:59 create_dir lib/kobject.c:63 [inline] kobject_add_internal+0x6b8/0xc80 lib/kobject.c:231 kobject_add_varg lib/kobject.c:366 [inline] kobject_init_and_add+0x122/0x190 lib/kobject.c:449 rx_queue_add_kobject net/core/net-sysfs.c:1061 [inline] net_rx_queue_update_kobjects+0x1cd/0x4a0 net/core/net-sysfs.c:1112 register_queue_kobjects net/core/net-sysfs.c:1772 [inline] netdev_register_kobject+0x223/0x310 net/core/net-sysfs.c:2017 register_netdevice+0x12b9/0x1aa0 net/core/dev.c:10204 ppp_unit_register drivers/net/ppp/ppp_generic.c:1229 [inline] ppp_dev_configure+0x874/0xad0 drivers/net/ppp/ppp_generic.c:1285 ppp_create_interface drivers/net/ppp/ppp_generic.c:3362 [inline] ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1070 [inline] ppp_ioctl+0x65f/0x1940 drivers/net/ppp/ppp_generic.c:743 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f764378eba9 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:00007f76445e9038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f76439d6090 RCX: 00007f764378eba9 RDX: 000000110e22fff6 RSI: 00000000c004743e RDI: 0000000000000006 RBP: 00007f7643811e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f76439d6128 R14: 00007f76439d6090 R15: 00007ffcf2709878