KASAN: slab-out-of-bounds Read in hci_extended_inquiry_result_evt

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 399849e4 Linux 4.19.131
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1491e39b100000
kernel config: https://syzkaller.appspot.com/x/.config?x=eada6d424d8bae1d
dashboard link: https://syzkaller.appspot.com/bug?extid=5b7fc04f9e1c6b046b9f
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13f04c05100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12e1a8cb100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+5b7fc0...@syzkaller.appspotmail.com

audit: type=1400 audit(1593880341.274:8): avc: denied { execmem } for pid=6455 comm="syz-executor599" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
==================================================================
BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:373 [inline]
BUG: KASAN: slab-out-of-bounds in bacpy include/net/bluetooth/bluetooth.h:236 [inline]
BUG: KASAN: slab-out-of-bounds in hci_extended_inquiry_result_evt.isra.0+0x1aa/0x5b0 net/bluetooth/hci_event.c:4163
Read of size 6 at addr ffff88809e5311c4 by task kworker/u5:0/1218

CPU: 1 PID: 1218 Comm: kworker/u5:0 Not tainted 4.19.131-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+0x1fc/0x2fe lib/dump_stack.c:118
print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
kasan_report_error.cold+0x8a/0x1c7 mm/kasan/report.c:354
kasan_report+0x8f/0x96 mm/kasan/report.c:412
memcpy+0x20/0x50 mm/kasan/kasan.c:302
memcpy include/linux/string.h:373 [inline]
bacpy include/net/bluetooth/bluetooth.h:236 [inline]
hci_extended_inquiry_result_evt.isra.0+0x1aa/0x5b0 net/bluetooth/hci_event.c:4163
hci_event_packet+0x2025/0x858f net/bluetooth/hci_event.c:5845
hci_rx_work+0x46b/0xa90 net/bluetooth/hci_core.c:4359
process_one_work+0x864/0x1570 kernel/workqueue.c:2155
worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
kthread+0x30b/0x410 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 6470:
__do_kmalloc_node mm/slab.c:3689 [inline]
__kmalloc_node_track_caller+0x4c/0x70 mm/slab.c:3703
__kmalloc_reserve net/core/skbuff.c:137 [inline]
__alloc_skb+0xae/0x560 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+0xbd/0x450 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+0x51b/0x770 fs/read_write.c:487
vfs_write+0x1f3/0x540 fs/read_write.c:549
ksys_write+0x12b/0x2a0 fs/read_write.c:599
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 4701:
__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x210 mm/slab.c:3822
skb_free_head net/core/skbuff.c:554 [inline]
skb_release_data+0x6de/0x920 net/core/skbuff.c:574
skb_release_all net/core/skbuff.c:631 [inline]
__kfree_skb net/core/skbuff.c:645 [inline]
consume_skb+0x113/0x3d0 net/core/skbuff.c:705
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x4dd/0x690 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1909
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:632
___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2115
__sys_sendmsg net/socket.c:2153 [inline]
__do_sys_sendmsg net/socket.c:2162 [inline]
__se_sys_sendmsg net/socket.c:2160 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2160
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809e530dc0
which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 4 bytes to the right of
1024-byte region [ffff88809e530dc0, ffff88809e5311c0)
The buggy address belongs to the page:
page:ffffea0002794c00 count:1 mapcount:0 mapping:ffff88812c39cac0 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffffea000265ef08 ffffea00028f8108 ffff88812c39cac0
raw: 0000000000000000 ffff88809e530040 0000000100000007 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809e531080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88809e531100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88809e531180: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
^
ffff88809e531200: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff88809e531280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[syzbot]

syzbot suspects this issue was fixed by commit:

commit 8c4a649c20fec015ebb326f36b47d4e39d9ff5b7
Author: Peilin Ye <yepei...@gmail.com>
Date: Fri Jul 10 16:09:15 2020 +0000

Bluetooth: Fix slab-out-of-bounds read in hci_extended_inquiry_result_evt()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=107fbd3e900000
start commit: 13af6c74 Linux 4.19.136
git tree: linux-4.19.y
kernel config: https://syzkaller.appspot.com/x/.config?x=5b7578d3b5457a49
dashboard link: https://syzkaller.appspot.com/bug?extid=5b7fc04f9e1c6b046b9f
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=114c1114900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=120fce42900000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: Bluetooth: Fix slab-out-of-bounds read in hci_extended_inquiry_result_evt()

For information about bisection process see: https://goo.gl/tpsmEJ#bisection