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* [PATCH net,stable] cdc_ncm: fix divide-by-zero caused by invalid wMaxPacketSize
@ 2019-09-18 12:01 Bjørn Mork
  2019-09-18 12:26 ` divide error in cdc_ncm_update_rxtx_max syzbot
  2019-09-21 19:30 ` [PATCH net,stable] cdc_ncm: fix divide-by-zero caused by invalid wMaxPacketSize Jakub Kicinski
  0 siblings, 2 replies; 7+ messages in thread
From: Bjørn Mork @ 2019-09-18 12:01 UTC (permalink / raw)
  To: netdev
  Cc: linux-usb, Oliver Neukum, Bjørn Mork, syzbot+ce366e2b8296e25d84f5

Endpoints with zero wMaxPacketSize are not usable for transferring
data. Ignore such endpoints when looking for valid in, out and
status pipes, to make the driver more robust against invalid and
meaningless descriptors.

The wMaxPacketSize of the out pipe is used as divisor. So this change
fixes a divide-by-zero bug.

Reported-by: syzbot+ce366e2b8296e25d84f5@syzkaller.appspotmail.com
Signed-off-by: Bjørn Mork <bjorn@mork.no>
---
#syz test: https://github.com/google/kasan.git f0df5c1b

 drivers/net/usb/cdc_ncm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 50c05d0f44cb..00cab3f43a4c 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -681,8 +681,12 @@ cdc_ncm_find_endpoints(struct usbnet *dev, struct usb_interface *intf)
 	u8 ep;
 
 	for (ep = 0; ep < intf->cur_altsetting->desc.bNumEndpoints; ep++) {
-
 		e = intf->cur_altsetting->endpoint + ep;
+
+		/* ignore endpoints which cannot transfer data */
+		if (!usb_endpoint_maxp(&e->desc))
+			continue;
+
 		switch (e->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) {
 		case USB_ENDPOINT_XFER_INT:
 			if (usb_endpoint_dir_in(&e->desc)) {
-- 
2.20.1


^ permalink raw reply related	[flat|nested] 7+ messages in thread
* divide error in cdc_ncm_update_rxtx_max
@ 2019-09-16 13:29 syzbot
  2019-09-17 13:52 ` Bjørn Mork
  0 siblings, 1 reply; 7+ messages in thread
From: syzbot @ 2019-09-16 13:29 UTC (permalink / raw)
  To: andreyknvl, davem, linux-kernel, linux-usb, netdev, oliver,
	syzkaller-bugs

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+ce366e2b8296e25d84f5@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.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
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syzbot can test patches for this bug, for details see:
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^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2019-09-21 19:30 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-18 12:01 [PATCH net,stable] cdc_ncm: fix divide-by-zero caused by invalid wMaxPacketSize Bjørn Mork
2019-09-18 12:26 ` divide error in cdc_ncm_update_rxtx_max syzbot
2019-09-21 19:30 ` [PATCH net,stable] cdc_ncm: fix divide-by-zero caused by invalid wMaxPacketSize Jakub Kicinski
  -- strict thread matches above, loose matches on Subject: below --
2019-09-16 13:29 divide error in cdc_ncm_update_rxtx_max syzbot
2019-09-17 13:52 ` Bjørn Mork
2019-09-17 14:09   ` syzbot
2019-09-17 15:46     ` Bjørn Mork

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