Re: KASAN: slab-out-of-bounds Read in hdpvr_probe

From: syzbot <syzbot+79d18aac4bf1770dd050@syzkaller.appspotmail.com>
To: allison@lohutok.net, andreyknvl@google.com,
	gregkh@linuxfoundation.org, hverkuil@xs4all.nl,
	linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
	linux-usb@vger.kernel.org, mchehab@kernel.org,
	syzkaller-bugs@googlegroups.com, tglx@linutronix.de
Subject: Re: KASAN: slab-out-of-bounds Read in hdpvr_probe
Date: Mon, 01 Jul 2019 15:30:05 -0700	[thread overview]
Message-ID: <0000000000007c8a56058ca62b34@google.com> (raw)
In-Reply-To: <0000000000003fc6ef058c2db557@google.com>

syzbot has found a reproducer for the following crash on:

HEAD commit:    7829a896 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=17242ab3a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f6d4561982f71f63
dashboard link: https://syzkaller.appspot.com/bug?extid=79d18aac4bf1770dd050
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14740905a00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=133fd90ba00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+79d18aac4bf1770dd050@syzkaller.appspotmail.com

usb 1-1: config 0 interface 200 altsetting 0 bulk endpoint 0x84 has invalid  
maxpacket 0
usb 1-1: New USB device found, idVendor=2040, idProduct=4982,  
bcdDevice=f9.cf
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
==================================================================
BUG: KASAN: slab-out-of-bounds in string_nocheck+0x1d2/0x200  
lib/vsprintf.c:605
Read of size 1 at addr ffff8881c65ea220 by task kworker/1:1/22

CPU: 1 PID: 22 Comm: kworker/1:1 Not tainted 5.2.0-rc6+ #13
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+0xca/0x13e lib/dump_stack.c:113
  print_address_description+0x67/0x231 mm/kasan/report.c:188
  __kasan_report.cold+0x1a/0x32 mm/kasan/report.c:317
  kasan_report+0xe/0x20 mm/kasan/common.c:614
  string_nocheck+0x1d2/0x200 lib/vsprintf.c:605
  string+0xe5/0xf0 lib/vsprintf.c:668
  vsnprintf+0x7d3/0x14f0 lib/vsprintf.c:2503
  vscnprintf+0x29/0x80 lib/vsprintf.c:2606
  vprintk_store+0x40/0x4b0 kernel/printk/printk.c:1907
  vprintk_emit+0xc8/0x3e0 kernel/printk/printk.c:1968
  vprintk_func+0x75/0x113 kernel/printk/printk_safe.c:386
  printk+0xba/0xed kernel/printk/printk.c:2046
  device_authorization drivers/media/usb/hdpvr/hdpvr-core.c:140 [inline]
  hdpvr_device_init drivers/media/usb/hdpvr/hdpvr-core.c:201 [inline]
  hdpvr_probe.cold+0x194/0x1247 drivers/media/usb/hdpvr/hdpvr-core.c:342
  usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
  really_probe+0x281/0x660 drivers/base/dd.c:509
  driver_probe_device+0x104/0x210 drivers/base/dd.c:670
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
  bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
  __device_attach+0x217/0x360 drivers/base/dd.c:843
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
  device_add+0xae6/0x16f0 drivers/base/core.c:2111
  usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023
  generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
  usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
  really_probe+0x281/0x660 drivers/base/dd.c:509
  driver_probe_device+0x104/0x210 drivers/base/dd.c:670
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
  bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
  __device_attach+0x217/0x360 drivers/base/dd.c:843
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
  device_add+0xae6/0x16f0 drivers/base/core.c:2111
  usb_new_device.cold+0x8c1/0x1016 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+0x1ada/0x3590 drivers/usb/core/hub.c:5432
  process_one_work+0x905/0x1570 kernel/workqueue.c:2269
  process_scheduled_works kernel/workqueue.c:2331 [inline]
  worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
  kthread+0x30b/0x410 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 22:
  save_stack+0x1b/0x80 mm/kasan/common.c:71
  set_track mm/kasan/common.c:79 [inline]
  __kasan_kmalloc mm/kasan/common.c:489 [inline]
  __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:462
  kmalloc include/linux/slab.h:547 [inline]
  hdpvr_probe+0x1ce/0xac0 drivers/media/usb/hdpvr/hdpvr-core.c:297
  usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
  really_probe+0x281/0x660 drivers/base/dd.c:509
  driver_probe_device+0x104/0x210 drivers/base/dd.c:670
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
  bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
  __device_attach+0x217/0x360 drivers/base/dd.c:843
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
  device_add+0xae6/0x16f0 drivers/base/core.c:2111
  usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023
  generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
  usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
  really_probe+0x281/0x660 drivers/base/dd.c:509
  driver_probe_device+0x104/0x210 drivers/base/dd.c:670
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
  bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
  __device_attach+0x217/0x360 drivers/base/dd.c:843
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
  device_add+0xae6/0x16f0 drivers/base/core.c:2111
  usb_new_device.cold+0x8c1/0x1016 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+0x1ada/0x3590 drivers/usb/core/hub.c:5432
  process_one_work+0x905/0x1570 kernel/workqueue.c:2269
  process_scheduled_works kernel/workqueue.c:2331 [inline]
  worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
  kthread+0x30b/0x410 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8881c65ea1e0
  which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes to the right of
  64-byte region [ffff8881c65ea1e0, ffff8881c65ea220)
The buggy address belongs to the page:
page:ffffea0007197a80 refcount:1 mapcount:0 mapping:ffff8881dac03600  
index:0x0
flags: 0x200000000000200(slab)
raw: 0200000000000200 dead000000000100 dead000000000200 ffff8881dac03600
raw: 0000000000000000 00000000802a002a 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8881c65ea100: fc fc fc fc fb fb fb fb fb fb fb fb fc fc fc fc
  ffff8881c65ea180: fb fb fb fb fb fb fb fb fc fc fc fc 00 00 00 00
> ffff8881c65ea200: 00 00 00 00 fc fc fc fc fb fb fb fb fb fb fb fb
                                ^
  ffff8881c65ea280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff8881c65ea300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================