------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 7388 at lib/refcount.c:25 refcount_warn_saturate+0xdd/0x140 lib/refcount.c:25 Modules linked in: CPU: 0 PID: 7388 Comm: kworker/u5:1 Not tainted 5.12.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: hci2 hci_rx_work RIP: 0010:refcount_warn_saturate+0xdd/0x140 lib/refcount.c:25 Code: d0 4a e3 06 01 e8 48 73 ee 03 0f 0b eb 9d 80 3d bf 4a e3 06 00 75 94 48 c7 c7 a0 5a 12 88 c6 05 af 4a e3 06 01 e8 28 73 ee 03 <0f> 0b e9 7a ff ff ff 80 3d 99 4a e3 06 00 0f 85 6d ff ff ff 48 c7 RSP: 0018:ffffc90004647980 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff88811f959018 RCX: 0000000000000000 RDX: 0000000000000002 RSI: 0000000000000004 RDI: fffff520008c8f22 RBP: 0000000000000002 R08: 0000000000000001 R09: ffff8881f642095b R10: ffffed103ec8412b R11: 746e756f63666572 R12: dffffc0000000000 R13: 0000000000000001 R14: ffff88811f959021 R15: ffffffff8a20d248 FS: 0000000000000000(0000) GS:ffff8881f6400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000268e708 CR3: 0000000124478000 CR4: 0000000000350ef0 Call Trace: __refcount_add include/linux/refcount.h:199 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] kref_get include/linux/kref.h:45 [inline] l2cap_chan_hold net/bluetooth/l2cap_core.c:495 [inline] l2cap_global_chan_by_psm+0x35a/0x3c0 net/bluetooth/l2cap_core.c:1984 l2cap_conless_channel net/bluetooth/l2cap_core.c:7603 [inline] l2cap_recv_frame+0xa1f/0x9dd0 net/bluetooth/l2cap_core.c:7673 hci_acldata_packet net/bluetooth/hci_core.c:4902 [inline] hci_rx_work+0x38f/0x930 net/bluetooth/hci_core.c:5093 process_one_work+0x84c/0x13b0 kernel/workqueue.c:2275 worker_thread+0x598/0xf80 kernel/workqueue.c:2421 kthread+0x36f/0x450 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 irq event stamp: 79271 hardirqs last enabled at (79281): [] console_unlock+0x767/0xa00 kernel/printk/printk.c:2605 hardirqs last disabled at (79308): [] console_unlock+0x667/0xa00 kernel/printk/printk.c:2520 softirqs last enabled at (79306): [] invoke_softirq kernel/softirq.c:221 [inline] softirqs last enabled at (79306): [] __irq_exit_rcu kernel/softirq.c:422 [inline] softirqs last enabled at (79306): [] irq_exit_rcu+0x237/0x280 kernel/softirq.c:434 softirqs last disabled at (79327): [] invoke_softirq kernel/softirq.c:221 [inline] softirqs last disabled at (79327): [] __irq_exit_rcu kernel/softirq.c:422 [inline] softirqs last disabled at (79327): [] irq_exit_rcu+0x237/0x280 kernel/softirq.c:434 ---[ end trace dd8fd54b917134d2 ]--- ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 7388 at lib/refcount.c:28 refcount_warn_saturate+0x12b/0x140 lib/refcount.c:28 Modules linked in: CPU: 1 PID: 7388 Comm: kworker/u5:1 Tainted: G W 5.12.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: hci2 hci_rx_work RIP: 0010:refcount_warn_saturate+0x12b/0x140 lib/refcount.c:28 Code: 73 ee 03 0f 0b e9 53 ff ff ff 48 89 df e8 2d f1 4a fe e9 23 ff ff ff 48 c7 c7 00 5b 12 88 c6 05 60 4a e3 06 01 e8 da 72 ee 03 <0f> 0b e9 2c ff ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 41 RSP: 0018:ffffc90004647a68 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff88811f959018 RCX: 0000000000000000 RDX: 0000000000000001 RSI: ffffffff88129480 RDI: fffff520008c8f3f RBP: 0000000000000003 R08: 0000000000000001 R09: ffff8881f65310e7 R10: ffffed103eca621c R11: 0000000063666572 R12: ffff88811f959000 R13: ffff88811f959018 R14: ffff88811b04a014 R15: ffff88810fc1b140 FS: 0000000000000000(0000) GS:ffff8881f6500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000530198 CR3: 0000000102ccb000 CR4: 0000000000350ee0 Call Trace: __refcount_sub_and_test include/linux/refcount.h:283 [inline] __refcount_dec_and_test include/linux/refcount.h:315 [inline] refcount_dec_and_test include/linux/refcount.h:333 [inline] kref_put include/linux/kref.h:64 [inline] l2cap_chan_put net/bluetooth/l2cap_core.c:502 [inline] l2cap_conless_channel net/bluetooth/l2cap_core.c:7626 [inline] l2cap_recv_frame+0xb8a/0x9dd0 net/bluetooth/l2cap_core.c:7673 hci_acldata_packet net/bluetooth/hci_core.c:4902 [inline] hci_rx_work+0x38f/0x930 net/bluetooth/hci_core.c:5093 process_one_work+0x84c/0x13b0 kernel/workqueue.c:2275 worker_thread+0x598/0xf80 kernel/workqueue.c:2421 kthread+0x36f/0x450 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 irq event stamp: 80639 hardirqs last enabled at (80675): [] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline] hardirqs last enabled at (80675): [] _raw_spin_unlock_irq+0x1f/0x80 kernel/locking/spinlock.c:199 hardirqs last disabled at (80694): [] __schedule+0x1225/0x2180 kernel/sched/core.c:4972 softirqs last enabled at (80718): [] invoke_softirq kernel/softirq.c:221 [inline] softirqs last enabled at (80718): [] __irq_exit_rcu kernel/softirq.c:422 [inline] softirqs last enabled at (80718): [] irq_exit_rcu+0x237/0x280 kernel/softirq.c:434 softirqs last disabled at (80703): [] invoke_softirq kernel/softirq.c:221 [inline] softirqs last disabled at (80703): [] __irq_exit_rcu kernel/softirq.c:422 [inline] softirqs last disabled at (80703): [] irq_exit_rcu+0x237/0x280 kernel/softirq.c:434 ---[ end trace dd8fd54b917134d3 ]---