Re: general protection fault in cdev_del

[Andrey Konovalov]

On Tue, Aug 13, 2019 at 3:16 PM syzbot
<syzbot+67b2bd0e34f952d0321e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot has tested the proposed patch but the reproducer still triggered
> crash:
> KASAN: use-after-free Read in hso_free_interface
>
> ==================================================================
> BUG: KASAN: use-after-free in hso_free_interface+0x3f2/0x4f0
> drivers/net/usb/hso.c:3108
> Read of size 8 at addr ffff8881d112d998 by task kworker/0:1/12
>
> CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.2.0-rc1+ #1
> 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
>   hso_free_interface+0x3f2/0x4f0 drivers/net/usb/hso.c:3108
>   hso_probe+0x362/0x1a50 drivers/net/usb/hso.c:2963
>   usb_probe_interface+0x30b/0x7a0 drivers/usb/core/driver.c:361
>   really_probe+0x287/0x660 drivers/base/dd.c:509
>   driver_probe_device+0x104/0x210 drivers/base/dd.c:670
>   __device_attach_driver+0x1c4/0x230 drivers/base/dd.c:777
>   bus_for_each_drv+0x15e/0x1e0 drivers/base/bus.c:454
>   __device_attach+0x217/0x360 drivers/base/dd.c:843
>   bus_probe_device+0x1e6/0x290 drivers/base/bus.c:514
>   device_add+0xae6/0x1700 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+0xa2/0x100 drivers/usb/core/driver.c:266
>   really_probe+0x287/0x660 drivers/base/dd.c:509
>   driver_probe_device+0x104/0x210 drivers/base/dd.c:670
>   __device_attach_driver+0x1c4/0x230 drivers/base/dd.c:777
>   bus_for_each_drv+0x15e/0x1e0 drivers/base/bus.c:454
>   __device_attach+0x217/0x360 drivers/base/dd.c:843
>   bus_probe_device+0x1e6/0x290 drivers/base/bus.c:514
>   device_add+0xae6/0x1700 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+0x1adc/0x35a0 drivers/usb/core/hub.c:5432
>   process_one_work+0x90a/0x1580 kernel/workqueue.c:2268
>   worker_thread+0x96/0xe20 kernel/workqueue.c:2414
>   kthread+0x30e/0x420 kernel/kthread.c:254
>   ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
>
> Allocated by task 12:
>   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]
>   kzalloc include/linux/slab.h:742 [inline]
>   hso_create_device+0x43/0x390 drivers/net/usb/hso.c:2336
>   hso_create_bulk_serial_device drivers/net/usb/hso.c:2617 [inline]
>   hso_probe+0xbb0/0x1a50 drivers/net/usb/hso.c:2948
>   usb_probe_interface+0x30b/0x7a0 drivers/usb/core/driver.c:361
>   really_probe+0x287/0x660 drivers/base/dd.c:509
>   driver_probe_device+0x104/0x210 drivers/base/dd.c:670
>   __device_attach_driver+0x1c4/0x230 drivers/base/dd.c:777
>   bus_for_each_drv+0x15e/0x1e0 drivers/base/bus.c:454
>   __device_attach+0x217/0x360 drivers/base/dd.c:843
>   bus_probe_device+0x1e6/0x290 drivers/base/bus.c:514
>   device_add+0xae6/0x1700 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+0xa2/0x100 drivers/usb/core/driver.c:266
>   really_probe+0x287/0x660 drivers/base/dd.c:509
>   driver_probe_device+0x104/0x210 drivers/base/dd.c:670
>   __device_attach_driver+0x1c4/0x230 drivers/base/dd.c:777
>   bus_for_each_drv+0x15e/0x1e0 drivers/base/bus.c:454
>   __device_attach+0x217/0x360 drivers/base/dd.c:843
>   bus_probe_device+0x1e6/0x290 drivers/base/bus.c:514
>   device_add+0xae6/0x1700 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+0x1adc/0x35a0 drivers/usb/core/hub.c:5432
>   process_one_work+0x90a/0x1580 kernel/workqueue.c:2268
>   worker_thread+0x96/0xe20 kernel/workqueue.c:2414
>   kthread+0x30e/0x420 kernel/kthread.c:254
>   ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
>
> Freed by task 12:
>   save_stack+0x1b/0x80 mm/kasan/common.c:71
>   set_track mm/kasan/common.c:79 [inline]
>   __kasan_slab_free+0x130/0x180 mm/kasan/common.c:451
>   slab_free_hook mm/slub.c:1421 [inline]
>   slab_free_freelist_hook mm/slub.c:1448 [inline]
>   slab_free mm/slub.c:2994 [inline]
>   kfree+0xd7/0x290 mm/slub.c:3949
>   hso_create_bulk_serial_device drivers/net/usb/hso.c:2687 [inline]
>   hso_probe+0x13c6/0x1a50 drivers/net/usb/hso.c:2948
>   usb_probe_interface+0x30b/0x7a0 drivers/usb/core/driver.c:361
>   really_probe+0x287/0x660 drivers/base/dd.c:509
>   driver_probe_device+0x104/0x210 drivers/base/dd.c:670
>   __device_attach_driver+0x1c4/0x230 drivers/base/dd.c:777
>   bus_for_each_drv+0x15e/0x1e0 drivers/base/bus.c:454
>   __device_attach+0x217/0x360 drivers/base/dd.c:843
>   bus_probe_device+0x1e6/0x290 drivers/base/bus.c:514
>   device_add+0xae6/0x1700 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+0xa2/0x100 drivers/usb/core/driver.c:266
>   really_probe+0x287/0x660 drivers/base/dd.c:509
>   driver_probe_device+0x104/0x210 drivers/base/dd.c:670
>   __device_attach_driver+0x1c4/0x230 drivers/base/dd.c:777
>   bus_for_each_drv+0x15e/0x1e0 drivers/base/bus.c:454
>   __device_attach+0x217/0x360 drivers/base/dd.c:843
>   bus_probe_device+0x1e6/0x290 drivers/base/bus.c:514
>   device_add+0xae6/0x1700 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+0x1adc/0x35a0 drivers/usb/core/hub.c:5432
>   process_one_work+0x90a/0x1580 kernel/workqueue.c:2268
>   worker_thread+0x96/0xe20 kernel/workqueue.c:2414
>   kthread+0x30e/0x420 kernel/kthread.c:254
>   ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
>
> The buggy address belongs to the object at ffff8881d112d900
>   which belongs to the cache kmalloc-512 of size 512
> The buggy address is located 152 bytes inside of
>   512-byte region [ffff8881d112d900, ffff8881d112db00)
> The buggy address belongs to the page:
> page:ffffea0007444b00 refcount:1 mapcount:0 mapping:ffff8881dac02c00
> index:0x0 compound_mapcount: 0
> flags: 0x200000000010200(slab|head)
> raw: 0200000000010200 ffffea000744ea80 0000000400000004 ffff8881dac02c00
> raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>   ffff8881d112d880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>   ffff8881d112d900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ffff8881d112d980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                              ^
>   ffff8881d112da00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>   ffff8881d112da80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> Tested on:
>
> commit:         69bbe8c7 usb-fuzzer: main usb gadget fuzzer driver
> git tree:       https://github.com/google/kasan.git
> console output: https://syzkaller.appspot.com/x/log.txt?x=14e6156a600000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c309d28e15db39c5
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> patch:          https://syzkaller.appspot.com/x/patch.diff?x=1715ad4a600000
>

This bug looks very similar to the "KASAN: use-after-free Read in
device_del" one, but the fix from that thread doesn't work here.