netlink: 12 bytes leftover after parsing attributes in process `syz.0.848'. ================================ WARNING: inconsistent lock state 6.11.0-syzkaller-11993-g3efc57369a0c #0 Not tainted -------------------------------- inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. syz.0.848/10446 [HC0[0]:SC0[0]:HE1:SE1] takes: ffff88807d3df1e0 (&pch->downl){+.?.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88807d3df1e0 (&pch->downl){+.?.}-{2:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline] ffff88807d3df1e0 (&pch->downl){+.?.}-{2:2}, at: ppp_input+0x18b/0xa10 drivers/net/ppp/ppp_generic.c:2304 {IN-SOFTIRQ-W} state was registered at: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __ppp_channel_push+0x31/0x1e0 drivers/net/ppp/ppp_generic.c:2161 ppp_channel_push+0x196/0x220 drivers/net/ppp/ppp_generic.c:2192 tasklet_action_common+0x321/0x4d0 kernel/softirq.c:784 handle_softirqs+0x2c5/0x980 kernel/softirq.c:554 __do_softirq kernel/softirq.c:588 [inline] invoke_softirq kernel/softirq.c:428 [inline] __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637 irq_exit_rcu+0x9/0x30 kernel/softirq.c:649 common_interrupt+0xb9/0xd0 arch/x86/kernel/irq.c:278 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693 percpu_down_read include/linux/percpu-rwsem.h:63 [inline] __sb_start_write include/linux/fs.h:1716 [inline] sb_start_write+0xed/0x1c0 include/linux/fs.h:1852 mnt_want_write+0x3f/0x90 fs/namespace.c:515 do_unlinkat+0x1fe/0x830 fs/namei.c:4516 __do_sys_unlink fs/namei.c:4581 [inline] __se_sys_unlink fs/namei.c:4579 [inline] __ia32_sys_unlink+0x46/0x50 fs/namei.c:4579 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0xb4/0x110 arch/x86/entry/common.c:386 do_fast_syscall_32+0x34/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e irq event stamp: 6331 hardirqs last enabled at (6331): [] __local_bh_enable_ip+0x168/0x200 kernel/softirq.c:387 hardirqs last disabled at (6329): [] __local_bh_enable_ip+0x106/0x200 kernel/softirq.c:364 softirqs last enabled at (6330): [] spin_unlock_bh include/linux/spinlock.h:396 [inline] softirqs last enabled at (6330): [] __release_sock+0x9a/0x350 net/core/sock.c:3065 softirqs last disabled at (6328): [] spin_lock_bh include/linux/spinlock.h:356 [inline] softirqs last disabled at (6328): [] release_sock+0x30/0x1f0 net/core/sock.c:3624 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&pch->downl); lock(&pch->downl); *** DEADLOCK *** 2 locks held by syz.0.848/10446: #0: ffff888026e99258 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1609 [inline] #0: ffff888026e99258 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppoe_sendmsg+0x51/0x750 drivers/net/ppp/pppoe.c:849 #1: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #1: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2267 [inline] #1: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: ppp_input+0x55/0xa10 drivers/net/ppp/ppp_generic.c:2304 stack backtrace: CPU: 1 UID: 0 PID: 10446 Comm: syz.0.848 Not tainted 6.11.0-syzkaller-11993-g3efc57369a0c #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_usage_bug+0x62e/0x8b0 kernel/locking/lockdep.c:4035 valid_state+0x13a/0x1c0 kernel/locking/lockdep.c:4049 mark_lock_irq+0xbb/0xc20 kernel/locking/lockdep.c:4260 mark_lock+0x223/0x360 kernel/locking/lockdep.c:4722 __lock_acquire+0x11b0/0x2050 kernel/locking/lockdep.c:5153 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline] ppp_input+0x18b/0xa10 drivers/net/ppp/ppp_generic.c:2304 pppoe_rcv_core+0x117/0x310 drivers/net/ppp/pppoe.c:379 sk_backlog_rcv include/net/sock.h:1113 [inline] __release_sock+0x243/0x350 net/core/sock.c:3072 release_sock+0x61/0x1f0 net/core/sock.c:3626 pppoe_sendmsg+0xd5/0x750 drivers/net/ppp/pppoe.c:903 sock_sendmsg_nosec net/socket.c:729 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:744 ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2602 ___sys_sendmsg net/socket.c:2656 [inline] __sys_sendmmsg+0x4a8/0x730 net/socket.c:2735 __compat_sys_sendmmsg net/compat.c:360 [inline] __do_compat_sys_sendmmsg net/compat.c:367 [inline] __se_compat_sys_sendmmsg net/compat.c:364 [inline] __ia32_compat_sys_sendmmsg+0xa2/0xc0 net/compat.c:364 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0xb4/0x110 arch/x86/entry/common.c:386 do_fast_syscall_32+0x34/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf7f03579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 002b:00000000f568656c EFLAGS: 00000206 ORIG_RAX: 0000000000000159 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020009140 RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 90 nop 31: 90 nop 32: 90 nop 33: 90 nop 34: 90 nop 35: 90 nop 36: 90 nop 37: 90 nop 38: 90 nop 39: 90 nop 3a: 90 nop 3b: 90 nop 3c: 90 nop 3d: 90 nop