================================================================== BUG: KASAN: use-after-free in l2cap_chan_close+0x763/0xb10 net/bluetooth/l2cap_core.c:794 Read of size 1 at addr ffff888093197020 by task kworker/0:6/4000 CPU: 0 PID: 4000 Comm: kworker/0:6 Not tainted 5.7.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events do_enable_set Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:382 __kasan_report.cold+0x20/0x38 mm/kasan/report.c:511 kasan_report+0x33/0x50 mm/kasan/common.c:625 l2cap_chan_close+0x763/0xb10 net/bluetooth/l2cap_core.c:794 do_enable_set+0x4cf/0x8e0 net/bluetooth/6lowpan.c:1074 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268 worker_thread+0x96/0xe20 kernel/workqueue.c:2414 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351 Allocated by task 35: save_stack+0x1b/0x40 mm/kasan/common.c:49 set_track mm/kasan/common.c:57 [inline] __kasan_kmalloc mm/kasan/common.c:495 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468 kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] l2cap_chan_create+0x40/0x3a0 net/bluetooth/l2cap_core.c:450 chan_create+0xc/0xd0 net/bluetooth/6lowpan.c:640 bt_6lowpan_listen net/bluetooth/6lowpan.c:959 [inline] do_enable_set+0x511/0x8e0 net/bluetooth/6lowpan.c:1078 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268 worker_thread+0x96/0xe20 kernel/workqueue.c:2414 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351 Freed by task 35: save_stack+0x1b/0x40 mm/kasan/common.c:49 set_track mm/kasan/common.c:57 [inline] kasan_set_free_info mm/kasan/common.c:317 [inline] __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456 __cache_free mm/slab.c:3426 [inline] kfree+0x109/0x2b0 mm/slab.c:3757 l2cap_chan_destroy net/bluetooth/l2cap_core.c:488 [inline] kref_put include/linux/kref.h:65 [inline] l2cap_chan_put+0x1b2/0x230 net/bluetooth/l2cap_core.c:502 do_enable_set+0x4db/0x8e0 net/bluetooth/6lowpan.c:1075 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268 worker_thread+0x96/0xe20 kernel/workqueue.c:2414 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351 The buggy address belongs to the object at ffff888093197000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 32 bytes inside of 2048-byte region [ffff888093197000, ffff888093197800) The buggy address belongs to the page: page:ffffea00024c65c0 refcount:1 mapcount:0 mapping:00000000c923272b index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea000279b948 ffffea0002a40488 ffff8880aa000e00 raw: 0000000000000000 ffff888093197000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888093196f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888093196f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888093197000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888093197080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888093197100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================