KASAN: stack-out-of-bounds Read in string

KASAN: stack-out-of-bounds Read in string

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    9a33b369 usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan/tree/usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=116f9cd3200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=23e37f59d94ddd15
dashboard link: https://syzkaller.appspot.com/bug?extid=b75b85111c10b8d680f1
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=161ebce3200000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16fd974b200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+b75b85111c10b8d680f1@syzkaller.appspotmail.com

usb 1-1: config 0 has no interface number 0
usb 1-1: New USB device found, idVendor=0424, idProduct=012c,  
bcdDevice=1a.78
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
==================================================================
BUG: KASAN: stack-out-of-bounds in string+0x1f6/0x220 lib/vsprintf.c:606
Read of size 1 at addr ffff88809ee2f260 by task kworker/0:2/539

CPU: 0 PID: 539 Comm: kworker/0:2 Not tainted 5.1.0-rc4-319354-g9a33b36 #3
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
  string+0x1f6/0x220 lib/vsprintf.c:606
  vsnprintf+0xa14/0x16b0 lib/vsprintf.c:2396
  pointer+0x60b/0x910 lib/vsprintf.c:2038
  vsnprintf+0x5a0/0x16b0 lib/vsprintf.c:2400
  vscnprintf+0x29/0x80 lib/vsprintf.c:2499
  vprintk_store+0x45/0x4a0 kernel/printk/printk.c:1900
  vprintk_emit+0x210/0x5a0 kernel/printk/printk.c:1957
  dev_vprintk_emit+0x50e/0x553 drivers/base/core.c:3185
  dev_printk_emit+0xbf/0xf6 drivers/base/core.c:3196
  __dev_printk+0x1ed/0x215 drivers/base/core.c:3208
  _dev_info+0xdc/0x10e drivers/base/core.c:3254
  vub300_probe+0x25e/0xd80 drivers/mmc/host/vub300.c:2109
  usb_probe_interface+0x31d/0x820 drivers/usb/core/driver.c:361
  really_probe+0x2da/0xb10 drivers/base/dd.c:509
  driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
  __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
  bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
  __device_attach+0x223/0x3a0 drivers/base/dd.c:844
  bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
  device_add+0xad2/0x16e0 drivers/base/core.c:2106
  usb_set_configuration+0xdf7/0x1740 drivers/usb/core/message.c:2021
  generic_probe+0xa2/0xda drivers/usb/core/generic.c:210
  usb_probe_device+0xc0/0x150 drivers/usb/core/driver.c:266
  really_probe+0x2da/0xb10 drivers/base/dd.c:509
  driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
  __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
  bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
  __device_attach+0x223/0x3a0 drivers/base/dd.c:844
  bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
  device_add+0xad2/0x16e0 drivers/base/core.c:2106
  usb_new_device.cold+0x537/0xccf drivers/usb/core/hub.c:2534
  hub_port_connect drivers/usb/core/hub.c:5089 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
  port_event drivers/usb/core/hub.c:5350 [inline]
  hub_event+0x138e/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

The buggy address belongs to the page:
page:ffffea00027b8bc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfff00000000000()
raw: 00fff00000000000 ffffea00027b8bc8 ffffea00027b8bc8 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff88809ee2f100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  ffff88809ee2f180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffff88809ee2f200: 00 00 f1 f1 f1 f1 f1 f1 00 00 00 00 f2 f2 f2 f2
                                                        ^
  ffff88809ee2f280: 00 00 00 00 f2 f2 f2 f2 00 00 00 00 00 00 f3 f3
  ffff88809ee2f300: f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


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