bisecting fixing commit since 5692097116094a4a7045abcc1dbc172dbdc5657e
building syzkaller on 749688d22abef3f3cb9a0480e15c19a3f2ed8e13
testing commit 5692097116094a4a7045abcc1dbc172dbdc5657e with gcc (GCC) 8.1.0
kernel signature: df09f781c6b14ca8bca8407db1533beaf18c50889247eaa7021e8f40d4c4a0de
all runs: crashed: KASAN: slab-out-of-bounds Read in bacpy
testing current HEAD 6dd0e32665e591e9debe3edaf73c2f8135bf047e
testing commit 6dd0e32665e591e9debe3edaf73c2f8135bf047e with gcc (GCC) 8.1.0
kernel signature: bee8b5913b160aae6040592bee9b92ad99211eca0645f153142ab99c39abbcec
all runs: crashed: KASAN: slab-out-of-bounds Read in bacpy
revisions tested: 2, total time: 24m25.113453592s (build: 17m30.92515073s, test: 6m9.518279681s)
the crash still happens on HEAD
commit msg: Linux 4.19.115
crash: KASAN: slab-out-of-bounds Read in bacpy
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes 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 ffff88808b841e88 by task kworker/u5:2/7904

CPU: 1 PID: 7904 Comm: kworker/u5:2 Not tainted 4.19.115-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
 hci_rx_work+0x363/0x8f0 net/bluetooth/hci_core.c:4359
 process_one_work+0x830/0x1670 kernel/workqueue.c:2155
 worker_thread+0x85/0xb60 kernel/workqueue.c:2298
 kthread+0x324/0x3e0 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 7899:
 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
 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)

The buggy address belongs to the object at ffff88808b841c80
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes to the right of
 512-byte region [ffff88808b841c80, ffff88808b841e80)
The buggy address belongs to the page:
page:ffffea00022e1040 count:1 mapcount:0 mapping:ffff88812c29c940 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffffea00022ddf08 ffffea000234ce08 ffff88812c29c940
raw: 0000000000000000 ffff88808b841000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808b841d80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88808b841e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88808b841e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                      ^
 ffff88808b841f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88808b841f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================