KASAN: use-after-free Read in __smsc95xx_mdio_read

KASAN: use-after-free Read in __smsc95xx_mdio_read

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    7ae77150 Merge tag 'powerpc-5.8-1' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15f83346100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d195fe572fb15312
dashboard link: https://syzkaller.appspot.com/bug?extid=a7ebdb01bb2cc165cab6
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17046c66100000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=140a8a3e100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a7ebdb01bb2cc165cab6@syzkaller.appspotmail.com

smsc95xx 1-1:1.0 eth6: Failed to read reg index 0x00000114: -19
smsc95xx 1-1:1.0 eth6 (unregistering): Error reading MII_ACCESS
smsc95xx 1-1:1.0 eth6 (unregistered): MII is busy in smsc95xx_mdio_read
==================================================================
BUG: KASAN: use-after-free in atomic64_read include/asm-generic/atomic-instrumented.h:836 [inline]
BUG: KASAN: use-after-free in atomic_long_read include/asm-generic/atomic-long.h:28 [inline]
BUG: KASAN: use-after-free in __mutex_unlock_slowpath+0x8e/0x660 kernel/locking/mutex.c:1237
Read of size 8 at addr ffff888094310c38 by task kworker/0:4/6949

CPU: 0 PID: 6949 Comm: kworker/0:4 Not tainted 5.7.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events check_carrier
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0x141/0x190 mm/kasan/generic.c:192
 atomic64_read include/asm-generic/atomic-instrumented.h:836 [inline]
 atomic_long_read include/asm-generic/atomic-long.h:28 [inline]
 __mutex_unlock_slowpath+0x8e/0x660 kernel/locking/mutex.c:1237
 __smsc95xx_mdio_read+0x1bc/0x210 drivers/net/usb/smsc95xx.c:217
 smsc95xx_mdio_read drivers/net/usb/smsc95xx.c:278 [inline]
 check_carrier+0xf3/0x1d0 drivers/net/usb/smsc95xx.c:644
 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
 worker_thread+0x96/0xe20 kernel/workqueue.c:2414
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

Allocated by task 6949:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc mm/kasan/common.c:494 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:467
 kmalloc_node include/linux/slab.h:578 [inline]
 kvmalloc_node+0xb4/0xf0 mm/util.c:574
 kvmalloc include/linux/mm.h:752 [inline]
 kvzalloc include/linux/mm.h:760 [inline]
 alloc_netdev_mqs+0x97/0xdc0 net/core/dev.c:9927
 usbnet_probe+0x159/0x2600 drivers/net/usb/usbnet.c:1686
 usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:374
 really_probe+0x281/0x6d0 drivers/base/dd.c:520
 driver_probe_device+0x104/0x210 drivers/base/dd.c:697
 __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:804
 bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:431
 __device_attach+0x21a/0x360 drivers/base/dd.c:870
 bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
 device_add+0x132d/0x1c10 drivers/base/core.c:2557
 usb_set_configuration+0xec5/0x1740 drivers/usb/core/message.c:2032
 usb_generic_driver_probe+0x9d/0xe0 drivers/usb/core/generic.c:241
 usb_probe_device+0xc6/0x1f0 drivers/usb/core/driver.c:272
 really_probe+0x281/0x6d0 drivers/base/dd.c:520
 driver_probe_device+0x104/0x210 drivers/base/dd.c:697
 __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:804
 bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:431
 __device_attach+0x21a/0x360 drivers/base/dd.c:870
 bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
 device_add+0x132d/0x1c10 drivers/base/core.c:2557
 usb_new_device.cold+0x753/0x103d drivers/usb/core/hub.c:2554
 hub_port_connect drivers/usb/core/hub.c:5208 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5348 [inline]
 port_event drivers/usb/core/hub.c:5494 [inline]
 hub_event+0x1eca/0x38f0 drivers/usb/core/hub.c:5576
 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
 worker_thread+0x96/0xe20 kernel/workqueue.c:2414
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

Freed by task 6849:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x109/0x2b0 mm/slab.c:3757
 kvfree+0x42/0x50 mm/util.c:603
 device_release+0x71/0x200 drivers/base/core.c:1394
 kobject_cleanup lib/kobject.c:693 [inline]
 kobject_release lib/kobject.c:722 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1e7/0x2e0 lib/kobject.c:739
 put_device+0x1b/0x30 drivers/base/core.c:2656
 free_netdev+0x380/0x4a0 net/core/dev.c:10047
 usbnet_disconnect+0x1fb/0x270 drivers/net/usb/usbnet.c:1625
 usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:436
 __device_release_driver drivers/base/dd.c:1110 [inline]
 device_release_driver_internal+0x432/0x500 drivers/base/dd.c:1141
 bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:533
 device_del+0x481/0xd30 drivers/base/core.c:2734
 usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1245
 usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2217
 hub_port_connect drivers/usb/core/hub.c:5059 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5348 [inline]
 port_event drivers/usb/core/hub.c:5494 [inline]
 hub_event+0x17ca/0x38f0 drivers/usb/core/hub.c:5576
 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
 worker_thread+0x96/0xe20 kernel/workqueue.c:2414
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

The buggy address belongs to the object at ffff888094310000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 3128 bytes inside of
 8192-byte region [ffff888094310000, ffff888094312000)
The buggy address belongs to the page:
page:ffffea000250c400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea000250c400 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0002257808 ffffea0002548608 ffff8880aa0021c0
raw: 0000000000000000 ffff888094310000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888094310b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888094310b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888094310c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff888094310c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888094310d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This bug is generated by a bot. It may contain errors.
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Re: KASAN: use-after-free Read in __smsc95xx_mdio_read

[syzbot]

syzbot suspects this issue was fixed by commit:

commit 7e23ab72e73bc601b4cf2983382691d9f165c8d1
Author: Ding Xiang <dingxiang@cmss.chinamobile.com>
Date:   Mon Mar 30 07:56:26 2020 +0000

    pinctrl: nomadik:remove unneeded variable

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13cfe3a0900000
start commit:   7ae77150 Merge tag 'powerpc-5.8-1' of git://git.kernel.org..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=d195fe572fb15312
dashboard link: https://syzkaller.appspot.com/bug?extid=a7ebdb01bb2cc165cab6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17046c66100000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=140a8a3e100000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: pinctrl: nomadik:remove unneeded variable

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: KASAN: use-after-free Read in __smsc95xx_mdio_read

[Greg KH]

On Sun, Jul 26, 2020 at 02:57:05AM -0700, syzbot wrote:
> syzbot suspects this issue was fixed by commit:
> 
> commit 7e23ab72e73bc601b4cf2983382691d9f165c8d1
> Author: Ding Xiang <dingxiang@cmss.chinamobile.com>
> Date:   Mon Mar 30 07:56:26 2020 +0000
> 
>     pinctrl: nomadik:remove unneeded variable
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13cfe3a0900000
> start commit:   7ae77150 Merge tag 'powerpc-5.8-1' of git://git.kernel.org..
> git tree:       upstream
> kernel config:  https://syzkaller.appspot.com/x/.config?x=d195fe572fb15312
> dashboard link: https://syzkaller.appspot.com/bug?extid=a7ebdb01bb2cc165cab6
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17046c66100000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=140a8a3e100000
> 
> If the result looks correct, please mark the issue as fixed by replying with:

I think the bisection logic needs to be worked on a bit better, as how
can this patch resolve the reported problem?

thanks,

greg k-h