divide error in cdc_ncm_update_rxtx_max

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: f0df5c1b 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=14cd1459600000
kernel config: https://syzkaller.appspot.com/x/.config?x=5c6633fa4ed00be5
dashboard link: https://syzkaller.appspot.com/bug?extid=ce366e2b8296e25d84f5
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12b4dd85600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=179b7fc1600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ce366e...@syzkaller.appspotmail.com

cdc_ncm 1-1:1.0: dwNtbInMaxSize=0 is too small. Using 2048
cdc_ncm 1-1:1.0: setting rx_max = 2048
cdc_ncm 1-1:1.0: setting tx_max = 16384
divide error: 0000 [#1] SMP KASAN
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.3.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
RIP: 0010:cdc_ncm_update_rxtx_max+0xc6e/0xef0 drivers/net/usb/cdc_ncm.c:419
Code: e0 07 38 c2 0f 9e c1 84 d2 0f 95 c0 84 c1 0f 85 35 02 00 00 0f b7 5b
04 81 e3 ff 07 00 00 e8 29 47 f7 fd 31 d2 44 89 e0 31 ff <f7> f3 41 89 d5
89 d6 e8 86 48 f7 fd 45 85 ed 0f 85 17 f7 ff ff e8
RSP: 0018:ffff8881da20f030 EFLAGS: 00010246
RAX: 0000000000004000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff83469377 RDI: 0000000000000000
RBP: ffff8881c7ba0000 R08: ffff8881da1f9800 R09: ffffed103b645d58
R10: ffffed103b645d57 R11: ffff8881db22eabf R12: 0000000000004000
R13: 0000000000000000 R14: ffff8881d35f3dc0 R15: ffff8881d2a70f00
FS: 0000000000000000(0000) GS:ffff8881db200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1059879000 CR3: 00000001d49db000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
cdc_ncm_setup drivers/net/usb/cdc_ncm.c:667 [inline]
cdc_ncm_bind_common+0x1005/0x2570 drivers/net/usb/cdc_ncm.c:924
cdc_ncm_bind+0x7c/0x1c0 drivers/net/usb/cdc_ncm.c:1038
usbnet_probe+0xb43/0x23cf drivers/net/usb/usbnet.c:1722
usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
really_probe+0x281/0x6d0 drivers/base/dd.c:548
driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2165
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+0x281/0x6d0 drivers/base/dd.c:548
driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2165
usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2536
hub_port_connect drivers/usb/core/hub.c:5098 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x1b5c/0x3640 drivers/usb/core/hub.c:5441
process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
worker_thread+0x96/0xe20 kernel/workqueue.c:2415
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
---[ end trace ab75cc10e099d8e9 ]---
RIP:


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Bjørn Mork]

#syz test: https://github.com/google/kasan.git f0df5c1b

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer still triggered
crash:
divide error in usbnet_update_max_qlen

cdc_ncm 5-1:1.0: setting tx_max = 16384

divide error: 0000 [#1] SMP KASAN

CPU: 1 PID: 1737 Comm: kworker/1:2 Not tainted 5.3.0-rc7+ #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: usb_hub_wq hub_event

RIP: 0010:usbnet_update_max_qlen drivers/net/usb/usbnet.c:344 [inline]
RIP: 0010:usbnet_update_max_qlen+0x231/0x370 drivers/net/usb/usbnet.c:338
Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 46 01
00 00 48 8d bb f4 00 00 00 31 d2 b8 c8 63 01 00 48 89 f9 <48> f7 b3 a8 01
00 00 48 ba 00 00 00 00 00 fc ff df 48 c1 e9 03 0f
RSP: 0018:ffff8881c05c7010 EFLAGS: 00010246
RAX: 00000000000163c8 RBX: ffff8881c7334ec0 RCX: ffff8881c7334fb4
RDX: 0000000000000000 RSI: ffffffff8344ecde RDI: ffff8881c7334fb4
RBP: 0000000000000003 R08: ffff8881d4a9b000 R09: ffffed1038e6688a
R10: ffffed1038e66889 R11: ffff8881c733444f R12: 0000000000004000
R13: ffff8881c7334ec0 R14: 0000000000000000 R15: ffff8881d62e77ac
FS: 0000000000000000(0000) GS:ffff8881db300000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f5a513e8000 CR3: 00000001d6436000 CR4: 00000000001406e0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:

cdc_ncm_update_rxtx_max+0xa61/0xf30 drivers/net/usb/cdc_ncm.c:437
cdc_ncm_setup drivers/net/usb/cdc_ncm.c:664 [inline]
cdc_ncm_bind_common+0x1005/0x2570 drivers/net/usb/cdc_ncm.c:921
cdc_ncm_bind+0x7c/0x1c0 drivers/net/usb/cdc_ncm.c:1035

---[ end trace 472dbe98145a6d5e ]---
RIP: 0010:usbnet_update_max_qlen drivers/net/usb/usbnet.c:344 [inline]
RIP: 0010:usbnet_update_max_qlen+0x231/0x370 drivers/net/usb/usbnet.c:338
Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 46 01
00 00 48 8d bb f4 00 00 00 31 d2 b8 c8 63 01 00 48 89 f9 <48> f7 b3 a8 01
00 00 48 ba 00 00 00 00 00 fc ff df 48 c1 e9 03 0f
RSP: 0018:ffff8881c05c7010 EFLAGS: 00010246
RAX: 00000000000163c8 RBX: ffff8881c7334ec0 RCX: ffff8881c7334fb4
RDX: 0000000000000000 RSI: ffffffff8344ecde RDI: ffff8881c7334fb4
RBP: 0000000000000003 R08: ffff8881d4a9b000 R09: ffffed1038e6688a
R10: ffffed1038e66889 R11: ffff8881c733444f R12: 0000000000004000
R13: ffff8881c7334ec0 R14: 0000000000000000 R15: ffff8881d62e77ac
FS: 0000000000000000(0000) GS:ffff8881db300000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f5a513e8000 CR3: 00000001d6436000 CR4: 00000000001406e0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Tested on:

commit: f0df5c1b 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=173ea979600000

kernel config: https://syzkaller.appspot.com/x/.config?x=5c6633fa4ed00be5
dashboard link: https://syzkaller.appspot.com/bug?extid=ce366e2b8296e25d84f5
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

patch: https://syzkaller.appspot.com/x/patch.diff?x=1538611d600000

[Bjørn Mork]

syzbot <syzbot+ce366e...@syzkaller.appspotmail.com> writes:

> syzbot has tested the proposed patch but the reproducer still
> triggered crash:
> divide error in usbnet_update_max_qlen
>
> cdc_ncm 5-1:1.0: setting tx_max = 16384
> divide error: 0000 [#1] SMP KASAN
> CPU: 1 PID: 1737 Comm: kworker/1:2 Not tainted 5.3.0-rc7+ #0
> Hardware name: Google Google Compute Engine/Google Compute Engine,
> BIOS Google 01/01/2011
> Workqueue: usb_hub_wq hub_event
> RIP: 0010:usbnet_update_max_qlen drivers/net/usb/usbnet.c:344 [inline]
> RIP: 0010:usbnet_update_max_qlen+0x231/0x370 drivers/net/usb/usbnet.c:338

Sure, but that's another error already fixed by Oliver..

I guess this fix worked. But I believe we should see if this is a more
generic issue than just this single driver/bug. I fear it is...



Bjørn

[syzbot]

> #syz test: https://github.com/bmork/kasan.git kazan-usb-test

Bugs found by USB fuzzer can only be tested on
https://github.com/google/kasan.git tree,
usb-fuzzer branch because USB fuzzer is not upstreamed yet.
See https://goo.gl/tpsmEJ#usb-fuzzer for details.

[Andrey Konovalov]

Hi Bjørn,

I think you can just merge the two patches together and attach them to
the email as one.

Thanks!

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[Bjørn Mork]

[Bjørn Mork]

Yes, thanks, I realized that I had to do that.

Just thought I'd be "smarter" and have a tree (cloned from
https://github.com/google/kasan.git ) ready for the next bugs...


Bjørn

[Andrey Konovalov]

Yeah, we deliberately disallow to use any other kernel branches, as
the patches on the usb-fuzzer branch change from time to time, and
people will be required to keep track of which bug was reported on
which version of the patches.

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger
crash:

Reported-and-tested-by:
syzbot+ce366e...@syzkaller.appspotmail.com

Tested on:

commit: f0df5c1b usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git

kernel config: https://syzkaller.appspot.com/x/.config?x=5c6633fa4ed00be5
dashboard link: https://syzkaller.appspot.com/bug?extid=ce366e2b8296e25d84f5
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

patch: https://syzkaller.appspot.com/x/patch.diff?x=170510ad600000

Note: testing is done by a robot and is best-effort only.

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger
crash:

Reported-and-tested-by:
syzbot+ce366e...@syzkaller.appspotmail.com

Tested on:

commit: f0df5c1b usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git
kernel config: https://syzkaller.appspot.com/x/.config?x=5c6633fa4ed00be5
dashboard link: https://syzkaller.appspot.com/bug?extid=ce366e2b8296e25d84f5
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

patch: https://syzkaller.appspot.com/x/patch.diff?x=114971b5600000