Re: crash by cdc_acm driver in kernels 4.8-rc1/5

[Wim Osterholt]

On Wed, Sep 28, 2016 at 11:16:04AM +0200, Oliver Neukum wrote:
> 
> Very good. This is a valid oops. We can do two things. When I
> decode it, seems to crash in acm_alloc_minor() which does not make
> sense. It is likely that our kernels or compilers are a bit different.
> Could you please call gdb on your kernel module cdc-acm.ko
> and do:
> 
> list *(acm_probe+0x4ee)
> 
> this should show you where it crashes.

Currently gcc-4.9.3-rc3.
This is from vanilla kernel 4.8-rc8

# gdb ./cdc-acm.ko
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Reading symbols from ./cdc-acm.ko...done.
(gdb) list *(acm_probe+0x4ee)
0x1c9b is in acm_probe (drivers/usb/class/cdc-acm.c:1346).
1341            acm->control = control_interface;
1342            acm->data = data_interface;
1343            acm->minor = minor;
1344            acm->dev = usb_dev;
1345            if (h.usb_cdc_acm_descriptor)
1346                    acm->ctrl_caps = h.usb_cdc_acm_descriptor->bmCapabilities;
1347            if (quirks & NO_CAP_LINE)
1348                    acm->ctrl_caps &= ~USB_CDC_CAP_LINE;
1349            acm->ctrlsize = ctrlsize;
1350            acm->readsize = readsize;
(gdb) quit

A new kernel is compiling now.

Regards, Wim.