------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 29013 at lib/refcount.c:25 refcount_warn_saturate+0x13d/0x1a0 lib/refcount.c:25 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 29013 Comm: syz-executor.2 Not tainted 5.8.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1f0/0x31e lib/dump_stack.c:118 panic+0x264/0x7a0 kernel/panic.c:231 __warn+0x227/0x250 kernel/panic.c:600 report_bug+0x1b1/0x2e0 lib/bug.c:198 handle_bug+0x42/0x80 arch/x86/kernel/traps.c:234 exc_invalid_op+0x16/0x40 arch/x86/kernel/traps.c:254 asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536 RIP: 0010:refcount_warn_saturate+0x13d/0x1a0 lib/refcount.c:25 Code: c7 43 89 15 89 31 c0 e8 a1 7f a6 fd 0f 0b eb a3 e8 58 dc d4 fd c6 05 0d ca ea 05 01 48 c7 c7 7a 89 15 89 31 c0 e8 83 7f a6 fd <0f> 0b eb 85 e8 3a dc d4 fd c6 05 f0 c9 ea 05 01 48 c7 c7 a6 89 15 RSP: 0018:ffffc9001a8a7b10 EFLAGS: 00010046 RAX: dfd733b829b0ab00 RBX: 0000000000000002 RCX: ffff88804edc0480 RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000 RBP: 0000000000000002 R08: ffffffff815e2099 R09: ffffed1015d041c3 R10: ffffed1015d041c3 R11: 0000000000000000 R12: fffffffffffffa78 R13: dffffc0000000000 R14: ffffc9001a8a7bf0 R15: ffff88804edc0480 refcount_add include/linux/refcount.h:206 [inline] refcount_inc include/linux/refcount.h:241 [inline] get_pid include/linux/pid.h:84 [inline] release_task+0x118e/0x1320 kernel/exit.c:197 exit_notify kernel/exit.c:681 [inline] do_exit+0x14d9/0x1f20 kernel/exit.c:826 do_group_exit+0x161/0x2d0 kernel/exit.c:903 get_signal+0x139b/0x1d30 kernel/signal.c:2743 arch_do_signal+0x33/0x610 arch/x86/kernel/signal.c:811 exit_to_user_mode_loop kernel/entry/common.c:135 [inline] exit_to_user_mode_prepare+0x8d/0x1b0 kernel/entry/common.c:166 syscall_exit_to_user_mode+0x5e/0x1a0 kernel/entry/common.c:241 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d239 Code: Bad RIP value. RSP: 002b:00007fe8669c8cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000118cf48 RCX: 000000000045d239 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000118cf48 RBP: 000000000118cf40 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffcda4182cf R14: 00007fe8669c99c0 R15: 000000000118cf4c Kernel Offset: disabled Rebooting in 86400 seconds..