------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 7381 at lib/refcount.c:25 refcount_warn_saturate+0xdd/0x140 lib/refcount.c:25 Modules linked in: CPU: 0 PID: 7381 Comm: kworker/u5:2 Not tainted 5.13.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: hci4 hci_rx_work RIP: 0010:refcount_warn_saturate+0xdd/0x140 lib/refcount.c:25 Code: 6e b0 df 06 01 e8 ce 80 f3 03 0f 0b eb 9d 80 3d 5d b0 df 06 00 75 94 48 c7 c7 80 0c 13 88 c6 05 4d b0 df 06 01 e8 ae 80 f3 03 <0f> 0b e9 7a ff ff ff 80 3d 37 b0 df 06 00 0f 85 6d ff ff ff 48 c7 RSP: 0018:ffffc90004e77980 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff8881254ca018 RCX: 0000000000000000 RDX: 0000000000000002 RSI: ffffffff88134660 RDI: fffff520009cef22 RBP: 0000000000000002 R08: 0000000000000001 R09: ffff8881f6430dc7 R10: ffffed103ec861b8 R11: 746e756f63666572 R12: dffffc0000000000 R13: 0000000000000001 R14: ffff8881254ca021 R15: ffffffff8a220108 FS: 0000000000000000(0000) GS:ffff8881f6400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000180 CR3: 00000001170a2000 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:497 [inline] l2cap_global_chan_by_psm+0x35a/0x3c0 net/bluetooth/l2cap_core.c:1986 l2cap_conless_channel net/bluetooth/l2cap_core.c:7611 [inline] l2cap_recv_frame+0xa1f/0x9de0 net/bluetooth/l2cap_core.c:7681 hci_acldata_packet net/bluetooth/hci_core.c:4907 [inline] hci_rx_work+0x38f/0x930 net/bluetooth/hci_core.c:5098 process_one_work+0x84c/0x13b0 kernel/workqueue.c:2276 worker_thread+0x598/0xf80 kernel/workqueue.c:2422 kthread+0x36f/0x450 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 irq event stamp: 9933 hardirqs last enabled at (9941): [] console_unlock+0x72b/0x9c0 kernel/printk/printk.c:2668 hardirqs last disabled at (9950): [] console_unlock+0x62b/0x9c0 kernel/printk/printk.c:2589 softirqs last enabled at (9576): [] invoke_softirq kernel/softirq.c:433 [inline] softirqs last enabled at (9576): [] __irq_exit_rcu kernel/softirq.c:637 [inline] softirqs last enabled at (9576): [] irq_exit_rcu+0x250/0x2a0 kernel/softirq.c:649 softirqs last disabled at (8641): [] invoke_softirq kernel/softirq.c:433 [inline] softirqs last disabled at (8641): [] __irq_exit_rcu kernel/softirq.c:637 [inline] softirqs last disabled at (8641): [] irq_exit_rcu+0x250/0x2a0 kernel/softirq.c:649 ---[ end trace d719403b2fb33ecd ]--- ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 7381 at lib/refcount.c:28 refcount_warn_saturate+0x12b/0x140 lib/refcount.c:28 Modules linked in: CPU: 0 PID: 7381 Comm: kworker/u5:2 Tainted: G W 5.13.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: hci4 hci_rx_work RIP: 0010:refcount_warn_saturate+0x12b/0x140 lib/refcount.c:28 Code: 80 f3 03 0f 0b e9 53 ff ff ff 48 89 df e8 0d ca 47 fe e9 23 ff ff ff 48 c7 c7 e0 0c 13 88 c6 05 fe af df 06 01 e8 60 80 f3 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:ffffc90004e77a68 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff8881254ca018 RCX: 0000000000000000 RDX: 0000000000000001 RSI: ffffffff88134660 RDI: fffff520009cef3f RBP: 0000000000000003 R08: 0000000000000001 R09: ffff8881f6430dc7 R10: ffffed103ec861b8 R11: 0000000063666572 R12: ffff8881254ca000 R13: ffff8881254ca018 R14: ffff8881087de014 R15: ffff888102e36200 FS: 0000000000000000(0000) GS:ffff8881f6400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000180 CR3: 000000000928e000 CR4: 0000000000350ef0 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:504 [inline] l2cap_conless_channel net/bluetooth/l2cap_core.c:7634 [inline] l2cap_recv_frame+0xb8a/0x9de0 net/bluetooth/l2cap_core.c:7681 hci_acldata_packet net/bluetooth/hci_core.c:4907 [inline] hci_rx_work+0x38f/0x930 net/bluetooth/hci_core.c:5098 process_one_work+0x84c/0x13b0 kernel/workqueue.c:2276 worker_thread+0x598/0xf80 kernel/workqueue.c:2422 kthread+0x36f/0x450 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 irq event stamp: 10903 hardirqs last enabled at (10935): [] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline] hardirqs last enabled at (10935): [] _raw_spin_unlock_irq+0x1f/0x80 kernel/locking/spinlock.c:199 hardirqs last disabled at (10968): [] __schedule+0x13e1/0x23d0 kernel/sched/core.c:5043 softirqs last enabled at (10990): [] invoke_softirq kernel/softirq.c:433 [inline] softirqs last enabled at (10990): [] __irq_exit_rcu kernel/softirq.c:637 [inline] softirqs last enabled at (10990): [] irq_exit_rcu+0x250/0x2a0 kernel/softirq.c:649 softirqs last disabled at (11005): [] invoke_softirq kernel/softirq.c:433 [inline] softirqs last disabled at (11005): [] __irq_exit_rcu kernel/softirq.c:637 [inline] softirqs last disabled at (11005): [] irq_exit_rcu+0x250/0x2a0 kernel/softirq.c:649 ---[ end trace d719403b2fb33ece ]---