bisecting fixing commit since 738d2902773e30939a982c8df7a7f94293659810
building syzkaller on 25a0186eba20ef6f4f657039ff02eff52a838b1c
testing commit 738d2902773e30939a982c8df7a7f94293659810 with gcc (GCC) 8.1.0
kernel signature: 021786b8e3f448f1e24e77539d6505eb7943a5a4a5f621cc9cfc8b9e368472a1
all runs: crashed: KASAN: slab-out-of-bounds Read in bacpy
testing current HEAD 051e6b7e34b9bd24f46725f74994a4d3a653966e
testing commit 051e6b7e34b9bd24f46725f74994a4d3a653966e with gcc (GCC) 8.1.0
kernel signature: 4b9b157e61c5bdf9dc05f514e06050ca8dffcdc6122d08b46716f7a1396acbff
all runs: crashed: KASAN: slab-out-of-bounds Read in bacpy
revisions tested: 2, total time: 20m26.819525565s (build: 12m20.63732655s, test: 7m7.004182797s)
the crash still happens on HEAD
commit msg: Merge tag 'hwmon-for-v5.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging
crash: KASAN: slab-out-of-bounds Read in bacpy
==================================================================
BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:381 [inline]
BUG: KASAN: slab-out-of-bounds in bacpy+0xe/0x10 include/net/bluetooth/bluetooth.h:255
Read of size 6 at addr ffff88809cad4608 by task kworker/u5:0/1607

CPU: 1 PID: 1607 Comm: kworker/u5:0 Not tainted 5.7.0-rc5-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+0x12d/0x187 lib/dump_stack.c:118
 print_address_description.constprop.8.cold.10+0x9/0x41c mm/kasan/report.c:382
 __kasan_report.cold.11+0x23/0x3a mm/kasan/report.c:511
 kasan_report+0x38/0x50 mm/kasan/common.c:625
 check_memory_region_inline mm/kasan/generic.c:187 [inline]
 check_memory_region+0x1cc/0x1f0 mm/kasan/generic.c:193
 memcpy+0x23/0x60 mm/kasan/common.c:106
 memcpy include/linux/string.h:381 [inline]
 bacpy+0xe/0x10 include/net/bluetooth/bluetooth.h:255
 hci_extended_inquiry_result_evt net/bluetooth/hci_event.c:4357 [inline]
 hci_event_packet+0x3195/0x9652 net/bluetooth/hci_event.c:6075
 hci_rx_work+0x18e/0x950 net/bluetooth/hci_core.c:4686
 process_one_work+0x893/0x1690 kernel/workqueue.c:2268
 worker_thread+0x85/0xb60 kernel/workqueue.c:2414
 kthread+0x354/0x420 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

Allocated by task 7999:
 save_stack+0x21/0x50 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc.constprop.17+0xc7/0xd0 mm/kasan/common.c:495
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:509
 __do_kmalloc_node mm/slab.c:3616 [inline]
 __kmalloc_node_track_caller+0x4d/0x70 mm/slab.c:3630
 __kmalloc_reserve.isra.46+0x2c/0xc0 net/core/skbuff.c:142
 __alloc_skb+0xd7/0x570 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1083 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:358 [inline]
 vhci_get_user drivers/bluetooth/hci_vhci.c:165 [inline]
 vhci_write+0xa8/0x3e0 drivers/bluetooth/hci_vhci.c:285
 call_write_iter include/linux/fs.h:1907 [inline]
 new_sync_write+0x400/0x7e0 fs/read_write.c:484
 __vfs_write+0x94/0x110 fs/read_write.c:497
 vfs_write+0x190/0x530 fs/read_write.c:559
 ksys_write+0x10b/0x220 fs/read_write.c:612
 __do_sys_write fs/read_write.c:624 [inline]
 __se_sys_write fs/read_write.c:621 [inline]
 __x64_sys_write+0x6e/0xb0 fs/read_write.c:621
 do_syscall_64+0xca/0x630 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff88809cad4400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes to the right of
 512-byte region [ffff88809cad4400, ffff88809cad4600)
The buggy address belongs to the page:
page:ffffea000272b500 refcount:1 mapcount:0 mapping:00000000e5a8f640 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00027367c8 ffffea00027cdf88 ffff8880aa400a80
raw: 0000000000000000 ffff88809cad4000 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809cad4500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88809cad4580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88809cad4600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                      ^
 ffff88809cad4680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809cad4700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================