[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 81.277111][ T27] audit: type=1800 audit(1583232789.110:25): pid=9505 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 81.296891][ T27] audit: type=1800 audit(1583232789.120:26): pid=9505 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 81.319738][ T27] audit: type=1800 audit(1583232789.120:27): pid=9505 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.242' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 527.095657][ T3186] ================================================================== [ 527.104078][ T3186] BUG: KASAN: use-after-free in l2cap_chan_close+0x661/0xa10 [ 527.111514][ T3186] Read of size 1 at addr ffff88809e4a4020 by task kworker/0:76/3186 [ 527.119495][ T3186] [ 527.121888][ T3186] CPU: 0 PID: 3186 Comm: kworker/0:76 Not tainted 5.6.0-rc3-syzkaller #0 [ 527.130302][ T3186] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 527.140467][ T3186] Workqueue: events do_enable_set [ 527.145520][ T3186] Call Trace: [ 527.148931][ T3186] dump_stack+0x197/0x210 [ 527.153279][ T3186] ? l2cap_chan_close+0x661/0xa10 [ 527.158404][ T3186] print_address_description.constprop.0.cold+0xd4/0x30b [ 527.165445][ T3186] ? l2cap_chan_close+0x661/0xa10 [ 527.170572][ T3186] ? l2cap_chan_close+0x661/0xa10 [ 527.175617][ T3186] __kasan_report.cold+0x1b/0x32 [ 527.180570][ T3186] ? l2cap_chan_close+0x661/0xa10 [ 527.185747][ T3186] kasan_report+0x12/0x20 [ 527.190096][ T3186] __asan_report_load1_noabort+0x14/0x20 [ 527.195772][ T3186] l2cap_chan_close+0x661/0xa10 [ 527.200636][ T3186] ? __kasan_check_read+0x11/0x20 [ 527.205674][ T3186] ? l2cap_send_i_or_rr_or_rnr+0x330/0x330 [ 527.211636][ T3186] do_enable_set+0x53f/0x960 [ 527.216339][ T3186] ? rcu_lockdep_current_cpu_online+0xe3/0x130 [ 527.222696][ T3186] ? lowpan_control_write+0x4b0/0x4b0 [ 527.228200][ T3186] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 527.233764][ T3186] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 527.239966][ T3186] ? trace_hardirqs_on+0x67/0x240 [ 527.245096][ T3186] process_one_work+0xa05/0x17a0 [ 527.250112][ T3186] ? mark_held_locks+0xf0/0xf0 [ 527.254914][ T3186] ? pwq_dec_nr_in_flight+0x320/0x320 [ 527.260300][ T3186] ? lock_acquire+0x190/0x410 [ 527.265014][ T3186] worker_thread+0x98/0xe40 [ 527.269634][ T3186] kthread+0x361/0x430 [ 527.273728][ T3186] ? process_one_work+0x17a0/0x17a0 [ 527.278944][ T3186] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 527.284778][ T3186] ret_from_fork+0x24/0x30 [ 527.289230][ T3186] [ 527.291564][ T3186] Allocated by task 3002: [ 527.296090][ T3186] save_stack+0x23/0x90 [ 527.300275][ T3186] __kasan_kmalloc.constprop.0+0xcf/0xe0 [ 527.305943][ T3186] kasan_kmalloc+0x9/0x10 [ 527.310958][ T3186] kmem_cache_alloc_trace+0x158/0x790 [ 527.316439][ T3186] l2cap_chan_create+0x45/0x3a0 [ 527.321289][ T3186] chan_create+0x10/0xe0 [ 527.325656][ T3186] do_enable_set+0x583/0x960 [ 527.330242][ T3186] process_one_work+0xa05/0x17a0 [ 527.335174][ T3186] worker_thread+0x98/0xe40 [ 527.339706][ T3186] kthread+0x361/0x430 [ 527.343780][ T3186] ret_from_fork+0x24/0x30 [ 527.348637][ T3186] [ 527.350959][ T3186] Freed by task 3002: [ 527.354946][ T3186] save_stack+0x23/0x90 [ 527.359115][ T3186] __kasan_slab_free+0x102/0x150 [ 527.364180][ T3186] kasan_slab_free+0xe/0x10 [ 527.368680][ T3186] kfree+0x10a/0x2c0 [ 527.372623][ T3186] l2cap_chan_put+0x1b7/0x240 [ 527.377317][ T3186] do_enable_set+0x54b/0x960 [ 527.381906][ T3186] process_one_work+0xa05/0x17a0 [ 527.386848][ T3186] worker_thread+0x98/0xe40 [ 527.391348][ T3186] kthread+0x361/0x430 [ 527.395412][ T3186] ret_from_fork+0x24/0x30 [ 527.399809][ T3186] [ 527.402129][ T3186] The buggy address belongs to the object at ffff88809e4a4000 [ 527.402129][ T3186] which belongs to the cache kmalloc-2k of size 2048 [ 527.416468][ T3186] The buggy address is located 32 bytes inside of [ 527.416468][ T3186] 2048-byte region [ffff88809e4a4000, ffff88809e4a4800) [ 527.429740][ T3186] The buggy address belongs to the page: [ 527.435383][ T3186] page:ffffea0002792900 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 [ 527.444479][ T3186] flags: 0xfffe0000000200(slab) [ 527.449336][ T3186] raw: 00fffe0000000200 ffffea00027dab48 ffffea000261cfc8 ffff8880aa400e00 [ 527.457923][ T3186] raw: 0000000000000000 ffff88809e4a4000 0000000100000001 0000000000000000 [ 527.466512][ T3186] page dumped because: kasan: bad access detected [ 527.472915][ T3186] [ 527.475239][ T3186] Memory state around the buggy address: [ 527.480969][ T3186] ffff88809e4a3f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 527.489822][ T3186] ffff88809e4a3f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 527.497893][ T3186] >ffff88809e4a4000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 527.506135][ T3186] ^ [ 527.511245][ T3186] ffff88809e4a4080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 527.519318][ T3186] ffff88809e4a4100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 527.527391][ T3186] ================================================================== [ 527.535462][ T3186] Disabling lock debugging due to kernel taint [ 527.551613][ T3186] Kernel panic - not syncing: panic_on_warn set ... [ 527.558286][ T3186] CPU: 0 PID: 3186 Comm: kworker/0:76 Tainted: G B 5.6.0-rc3-syzkaller #0 [ 527.568084][ T3186] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 527.578160][ T3186] Workqueue: events do_enable_set [ 527.583205][ T3186] Call Trace: [ 527.586512][ T3186] dump_stack+0x197/0x210 [ 527.590947][ T3186] panic+0x2e3/0x75c [ 527.594859][ T3186] ? add_taint.cold+0x16/0x16 [ 527.599673][ T3186] ? l2cap_chan_close+0x661/0xa10 [ 527.604707][ T3186] ? preempt_schedule+0x4b/0x60 [ 527.609598][ T3186] ? ___preempt_schedule+0x16/0x18 [ 527.614725][ T3186] ? trace_hardirqs_on+0x5e/0x240 [ 527.619764][ T3186] ? l2cap_chan_close+0x661/0xa10 [ 527.624807][ T3186] end_report+0x47/0x4f [ 527.629000][ T3186] ? l2cap_chan_close+0x661/0xa10 [ 527.634047][ T3186] __kasan_report.cold+0xe/0x32 [ 527.639037][ T3186] ? l2cap_chan_close+0x661/0xa10 [ 527.644151][ T3186] kasan_report+0x12/0x20 [ 527.648498][ T3186] __asan_report_load1_noabort+0x14/0x20 [ 527.654144][ T3186] l2cap_chan_close+0x661/0xa10 [ 527.659009][ T3186] ? __kasan_check_read+0x11/0x20 [ 527.664043][ T3186] ? l2cap_send_i_or_rr_or_rnr+0x330/0x330 [ 527.669884][ T3186] do_enable_set+0x53f/0x960 [ 527.674505][ T3186] ? rcu_lockdep_current_cpu_online+0xe3/0x130 [ 527.680680][ T3186] ? lowpan_control_write+0x4b0/0x4b0 [ 527.686072][ T3186] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 527.691637][ T3186] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 527.697717][ T3186] ? trace_hardirqs_on+0x67/0x240 [ 527.702758][ T3186] process_one_work+0xa05/0x17a0 [ 527.707706][ T3186] ? mark_held_locks+0xf0/0xf0 [ 527.712588][ T3186] ? pwq_dec_nr_in_flight+0x320/0x320 [ 527.717991][ T3186] ? lock_acquire+0x190/0x410 [ 527.722687][ T3186] worker_thread+0x98/0xe40 [ 527.727213][ T3186] kthread+0x361/0x430 [ 527.731293][ T3186] ? process_one_work+0x17a0/0x17a0 [ 527.736636][ T3186] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 527.742364][ T3186] ret_from_fork+0x24/0x30 [ 527.748185][ T3186] Kernel Offset: disabled [ 527.752577][ T3186] Rebooting in 86400 seconds..