KASAN: slab-out-of-bounds Write in usb_get_bos_descriptor

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    43151d6c usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=124794d8a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4183eeef650d1234
dashboard link: https://syzkaller.appspot.com/bug?extid=71f1e64501a309fcc012
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=176a53d0a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+71f1e64501a309fcc012@xxxxxxxxxxxxxxxxxxxxxxxxx

usb 1-1: Using ep0 maxpacket: 8
==================================================================
BUG: KASAN: slab-out-of-bounds in usb_get_bos_descriptor+0x8be/0x8fb  
drivers/usb/core/config.c:976
Write of size 1 at addr ffff8880a48e38ec by task kworker/0:2/533

CPU: 0 PID: 533 Comm: kworker/0:2 Not tainted 5.1.0-rc3-319004-g43151d6 #6
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xe8/0x16e lib/dump_stack.c:113
 print_address_description+0x6c/0x236 mm/kasan/report.c:187
 kasan_report.cold+0x1a/0x3c mm/kasan/report.c:317
 usb_get_bos_descriptor+0x8be/0x8fb drivers/usb/core/config.c:976
 hub_port_init+0x1671/0x2d30 drivers/usb/core/hub.c:4828
 hub_port_connect drivers/usb/core/hub.c:5021 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
 port_event drivers/usb/core/hub.c:5350 [inline]
 hub_event+0x11b8/0x3b00 drivers/usb/core/hub.c:5432
 process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
 worker_thread+0x9b/0xe20 kernel/workqueue.c:2415
 kthread+0x313/0x420 kernel/kthread.c:253
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 533:
 set_track mm/kasan/common.c:87 [inline]
 __kasan_kmalloc mm/kasan/common.c:497 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:470
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:742 [inline]
 usb_get_bos_descriptor+0x1e2/0x8fb drivers/usb/core/config.c:955
 hub_port_init+0x1671/0x2d30 drivers/usb/core/hub.c:4828
 hub_port_connect drivers/usb/core/hub.c:5021 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
 port_event drivers/usb/core/hub.c:5350 [inline]
 hub_event+0x11b8/0x3b00 drivers/usb/core/hub.c:5432
 process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
 worker_thread+0x9b/0xe20 kernel/workqueue.c:2415
 kthread+0x313/0x420 kernel/kthread.c:253
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Freed by task 16:
 set_track mm/kasan/common.c:87 [inline]
 __kasan_slab_free+0x130/0x180 mm/kasan/common.c:459
 slab_free_hook mm/slub.c:1429 [inline]
 slab_free_freelist_hook+0x5e/0x140 mm/slub.c:1456
 slab_free mm/slub.c:3003 [inline]
 kfree+0xce/0x290 mm/slub.c:3958
 security_cred_free+0xa7/0x100 security/security.c:1498
 put_cred_rcu+0x78/0x310 kernel/cred.c:118
 __rcu_reclaim kernel/rcu/rcu.h:227 [inline]
 rcu_do_batch kernel/rcu/tree.c:2475 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2788 [inline]
 rcu_core+0x83b/0x1a80 kernel/rcu/tree.c:2769
 __do_softirq+0x22a/0x8cd kernel/softirq.c:293

The buggy address belongs to the object at ffff8880a48e38e8
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 4 bytes inside of
 8-byte region [ffff8880a48e38e8, ffff8880a48e38f0)
The buggy address belongs to the page:
page:ffffea00029238c0 count:1 mapcount:0 mapping:ffff88812c3f5c00  
index:0xffff8880a48e3c90
flags: 0xfff00000000200(slab)
raw: 00fff00000000200 ffffea000297f6c0 0000001600000016 ffff88812c3f5c00
raw: ffff8880a48e3c90 0000000080aa00a2 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a48e3780: fb fc fc fb fc fc fb fc fc fb fc fc fb fc fc fb
 ffff8880a48e3800: fc fc fb fc fc fb fc fc fb fc fc fb fc fc fb fc
> ffff8880a48e3880: fc fb fc fc fb fc fc fb fc fc fb fc fc 01 fc fc
                                                          ^
 ffff8880a48e3900: fb fc fc fb fc fc fb fc fc fb fc fc fb fc fc fb
 ffff8880a48e3980: fc fc fb fc fc fb fc fc fb fc fc fb fc fc fb fc
==================================================================


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