bisecting fixing commit since fb683b5e3f53a73e761952735736180939a313df building syzkaller on 85f267515d439552478cbfcdee7e4d0609ff7310 testing commit fb683b5e3f53a73e761952735736180939a313df with gcc (GCC) 8.1.0 kernel signature: ec506e808b5f7f8a23bc199e70eb0f66bc8da1f474937d975679272fdb239b79 run #0: crashed: KASAN: use-after-free Read in hci_cmd_timeout run #1: crashed: KASAN: use-after-free Read in hci_cmd_timeout run #2: crashed: KASAN: use-after-free Read in hci_cmd_timeout run #3: crashed: KASAN: use-after-free Read in hci_cmd_timeout run #4: OK run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK testing current HEAD f25804f389846835535db255e7ba80eeed967ed7 testing commit f25804f389846835535db255e7ba80eeed967ed7 with gcc (GCC) 8.1.0 kernel signature: 81899cd4125b6e79c4cbcfd7bf909b121e5e44bfec17e9f9fb9e491bc21b7525 run #0: crashed: KASAN: use-after-free Read in hci_cmd_timeout run #1: crashed: KASAN: use-after-free Read in hci_cmd_timeout run #2: OK run #3: OK run #4: OK run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK revisions tested: 2, total time: 42m22.2788614s (build: 21m15.68522401s, test: 20m16.747391027s) the crash still happens on HEAD commit msg: Linux 4.19.106 crash: KASAN: use-after-free Read in hci_cmd_timeout Bluetooth: hci5: command tx timeout Bluetooth: hci3: Frame reassembly failed (-84) Bluetooth: hci5: Frame reassembly failed (-84) Bluetooth: hci0: Entering manufacturer mode failed (-110) ================================================================== BUG: KASAN: use-after-free in hci_cmd_timeout+0x1be/0x1d0 net/bluetooth/hci_core.c:2573 Read of size 8 at addr ffff888098712e18 by task kworker/1:3/7244 CPU: 1 PID: 7244 Comm: kworker/1:3 Not tainted 4.19.106-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events hci_cmd_timeout Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 hci_cmd_timeout+0x1be/0x1d0 net/bluetooth/hci_core.c:2573 process_one_work+0x830/0x1670 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Allocated by task 7249: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc+0x12e/0x730 mm/slab.c:3559 skb_clone+0x115/0x340 net/core/skbuff.c:1284 hci_cmd_work+0xd0/0x250 net/bluetooth/hci_core.c:4395 process_one_work+0x830/0x1670 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Freed by task 7305: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kmem_cache_free+0x83/0x290 mm/slab.c:3765 kfree_skbmem+0x89/0xf0 net/core/skbuff.c:586 __kfree_skb net/core/skbuff.c:646 [inline] kfree_skb+0x9f/0x280 net/core/skbuff.c:663 hci_dev_do_open+0x965/0xfe0 net/bluetooth/hci_core.c:1509 hci_power_on+0xe2/0x410 net/bluetooth/hci_core.c:2130 process_one_work+0x830/0x1670 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 The buggy address belongs to the object at ffff888098712d40 which belongs to the cache skbuff_head_cache of size 232 Bluetooth: hci4: Entering manufacturer mode failed (-110) The buggy address is located 216 bytes inside of 232-byte region [ffff888098712d40, ffff888098712e28) The buggy address belongs to the page: page:ffffea000261c480 count:1 mapcount:0 mapping:ffff88821bab69c0 index:0x0 flags: 0xfffe0000000100(slab) raw: 00fffe0000000100 ffffea00022553c8 ffffea0002816088 ffff88821bab69c0 raw: 0000000000000000 ffff8880987120c0 000000010000000c 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888098712d00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff888098712d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888098712e00: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc ^ ffff888098712e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888098712f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc ================================================================== Bluetooth: hci2: Entering manufacturer mode failed (-110)