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* KASAN: slab-out-of-bounds Read in hex_string
@ 2019-04-29 12:06 syzbot
  2019-04-29 20:07 ` Alan Stern
  0 siblings, 1 reply; 12+ messages in thread
From: syzbot @ 2019-04-29 12:06 UTC (permalink / raw)
  To: andreyknvl, gregkh, linux-kernel, linux-usb, rafael, syzkaller-bugs

Hello,

syzbot found the following crash on:

HEAD commit:    43151d6c 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=139ac37f200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4183eeef650d1234
dashboard link: https://syzkaller.appspot.com/bug?extid=a9fefd18c7b240f19c54
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17f3b338a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a9fefd18c7b240f19c54@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in hex_string+0x418/0x4b0 lib/vsprintf.c:975
Read of size 1 at addr ffff88821a41bd38 by task kworker/0:1/12

CPU: 0 PID: 12 Comm: kworker/0:1 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
  hex_string+0x418/0x4b0 lib/vsprintf.c:975
  pointer+0x460/0x910 lib/vsprintf.c:1985
  vsnprintf+0x5a0/0x16b0 lib/vsprintf.c:2400
  pointer+0x60b/0x910 lib/vsprintf.c:2038
  vsnprintf+0x5a0/0x16b0 lib/vsprintf.c:2400
  vscnprintf+0x29/0x80 lib/vsprintf.c:2499
  vprintk_store+0x45/0x4b0 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
  dlfb_parse_vendor_descriptor drivers/video/fbdev/udlfb.c:1532 [inline]
  dlfb_usb_probe.cold+0xb96/0x1701 drivers/video/fbdev/udlfb.c:1615
  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:2023
  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

Allocated by task 12:
  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]
  usb_get_configuration+0x313/0x32b0 drivers/usb/core/config.c:857
  usb_enumerate_device drivers/usb/core/hub.c:2367 [inline]
  usb_new_device+0x2fe/0x450 drivers/usb/core/hub.c:2503
  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

Freed by task 1464:
  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
  single_release+0x91/0xb0 fs/seq_file.c:597
  __fput+0x2df/0x8c0 fs/file_table.c:278
  task_work_run+0x149/0x1c0 kernel/task_work.c:113
  tracehook_notify_resume include/linux/tracehook.h:188 [inline]
  exit_to_usermode_loop+0x243/0x270 arch/x86/entry/common.c:166
  prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
  do_syscall_64+0x40c/0x4f0 arch/x86/entry/common.c:293
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88821a41bd20
  which belongs to the cache kmalloc-32 of size 32
The buggy address is located 24 bytes inside of
  32-byte region [ffff88821a41bd20, ffff88821a41bd40)
The buggy address belongs to the page:
page:ffffea00086906c0 count:1 mapcount:0 mapping:ffff88812c3f5800 index:0x0
flags: 0x57ff00000000200(slab)
raw: 057ff00000000200 dead000000000100 dead000000000200 ffff88812c3f5800
raw: 0000000000000000 0000000000550055 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff88821a41bc00: 00 00 00 fc fc fc 00 00 00 00 fc fc 00 00 00 00
  ffff88821a41bc80: fc fc 00 00 00 00 fc fc fb fb fb fb fc fc fb fb
> ffff88821a41bd00: fb fb fc fc 00 00 00 fc fc fc fb fb fb fb fc fc
                                         ^
  ffff88821a41bd80: 00 00 00 fc fc fc 00 00 00 fc fc fc fb fb fb fb
  ffff88821a41be00: fc fc fb fb fb fb fc fc fb fb fb fb fc fc 00 00
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

^ permalink raw reply	[flat|nested] 12+ messages in thread

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Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-04-29 12:06 KASAN: slab-out-of-bounds Read in hex_string syzbot
2019-04-29 20:07 ` Alan Stern
2019-04-29 20:07   ` Alan Stern
2019-04-29 20:24   ` Andrey Konovalov
2019-04-29 20:24     ` Andrey Konovalov
2019-04-29 20:52   ` syzbot
2019-04-29 20:52     ` syzbot
2019-04-29 21:09   ` Eric Biggers
2019-04-29 21:09     ` Eric Biggers
2019-04-30 14:13     ` Alan Stern
2019-04-30 14:13       ` Alan Stern
2019-08-13 12:55       ` Andrey Konovalov

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