bisecting fixing commit since c7ecf3e3a71c216327980f26b1e895ce9b07ad31
building syzkaller on 25a0186eba20ef6f4f657039ff02eff52a838b1c
testing commit c7ecf3e3a71c216327980f26b1e895ce9b07ad31 with gcc (GCC) 8.1.0
kernel signature: 36138e73e7b8a4b7f2bc48e401d148fb08fa2246ee8f8bfc1292793943a75ce7
all runs: crashed: KASAN: slab-out-of-bounds Read in bacpy
testing current HEAD 4707d8e5727387e36ea99c74d5ff0ad227700fd0
testing commit 4707d8e5727387e36ea99c74d5ff0ad227700fd0 with gcc (GCC) 8.1.0
kernel signature: 12c452ee84c13591133bb4c9b2274c86ef8b1014415158fe97a53da746a7266d
all runs: crashed: KASAN: slab-out-of-bounds Read in bacpy
revisions tested: 2, total time: 25m19.372856399s (build: 18m22.950900278s, test: 6m4.579005361s)
the crash still happens on HEAD
commit msg: Linux 4.19.126
crash: KASAN: slab-out-of-bounds Read in bacpy
IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): vxcan0: link becomes ready
8021q: adding VLAN 0 to HW filter on device batadv0
IPv6: ADDRCONF(NETDEV_UP): veth0_to_hsr: link is not ready
==================================================================
BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:348 [inline]
BUG: KASAN: slab-out-of-bounds in bacpy+0xe/0x10 include/net/bluetooth/bluetooth.h:236
Read of size 6 at addr ffff8880824e7748 by task kworker/u5:1/7500

CPU: 1 PID: 7500 Comm: kworker/u5:1 Not tainted 4.19.126-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci0 hci_rx_work
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
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:348 [inline]
 bacpy+0xe/0x10 include/net/bluetooth/bluetooth.h:236
 hci_extended_inquiry_result_evt net/bluetooth/hci_event.c:4162 [inline]
 hci_event_packet+0x38ce/0x9bfe net/bluetooth/hci_event.c:5844
IPv6: ADDRCONF(NETDEV_UP): veth1_to_hsr: link is not ready
 hci_rx_work+0x363/0x8f0 net/bluetooth/hci_core.c:4359
hsr0: Slave A (hsr_slave_0) is not up; please bring it up to get a fully working HSR network
 process_one_work+0x830/0x1670 kernel/workqueue.c:2155
 worker_thread+0x85/0xb60 kernel/workqueue.c:2298
hsr0: Slave B (hsr_slave_1) is not up; please bring it up to get a fully working HSR network
 kthread+0x324/0x3e0 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 7530:
IPv6: ADDRCONF(NETDEV_UP): hsr0: link is not ready
 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
 __do_kmalloc_node mm/slab.c:3689 [inline]
 __kmalloc_node_track_caller+0x50/0x70 mm/slab.c:3703
 __kmalloc_reserve.isra.41+0x2c/0xc0 net/core/skbuff.c:137
 __alloc_skb+0xd7/0x580 net/core/skbuff.c:205
IPv6: ADDRCONF(NETDEV_UP): vxcan0: link is not ready
 alloc_skb include/linux/skbuff.h:995 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:339 [inline]
 vhci_get_user drivers/bluetooth/hci_vhci.c:180 [inline]
 vhci_write+0xa8/0x3f0 drivers/bluetooth/hci_vhci.c:299
 call_write_iter include/linux/fs.h:1821 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x443/0x890 fs/read_write.c:487
 vfs_write+0x150/0x4d0 fs/read_write.c:549
 ksys_write+0x103/0x260 fs/read_write.c:599
 __do_sys_write fs/read_write.c:611 [inline]
 __se_sys_write fs/read_write.c:608 [inline]
 __x64_sys_write+0x6e/0xb0 fs/read_write.c:608
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
(stack is not available)

IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
The buggy address belongs to the object at ffff8880824e7540
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes to the right of
 512-byte region [ffff8880824e7540, ffff8880824e7740)
The buggy address belongs to the page:
page:ffffea00020939c0 count:1 mapcount:0 mapping:ffff88812c29c940 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffffea00024b9b48 ffffea000247eac8 ffff88812c29c940
8021q: adding VLAN 0 to HW filter on device batadv0
raw: 0000000000000000 ffff8880824e7040 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880824e7600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880824e7680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880824e7700: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
                                              ^
 ffff8880824e7780: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8880824e7800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================