Re: [tcpdump] coredump when launched in a ESX4 VM without interface parameter (#59)

[Guy Harris <guy () alum mit edu>]

On Mar 26, 2013, at 9:07 AM, Michael Richardson <mcr () sandelman ca> wrote:

> The fault seems to be inside of libusb:
>
> Using host libthread_db library "/usr/lib/libthread_db.so.1".
> Core was generated by `/usr/sbin/tcpdump icmp'.
> Program terminated with signal 11, Segmentation fault.
> #0  0x00007feae033fb50 in __opendirat () from /usr/lib/libc.so.6
> (gdb) bt
> #0  0x00007feae033fb50 in __opendirat () from /usr/lib/libc.so.6
> #1  0x00007feadfc68e9e in ?? () from /usr/lib/libusb-1.0.so.0
> #2  0x00007feadfc6153c in libusb_get_device_list () from
> /usr/lib/libusb-1.0.so.0
> #3  0x00007feae0647a9f in canusb_platform_finddevs () from
> /usr/lib/libpcap.so.1
>
> It appears that it faults if there are no USB devices, which wouldn't be
> surprising for a VM.

It faults because it's being handed a NULL first argument, and it's being handed a NULL argument because libpcap isn't 
checking whether libusb_init() succeeded or not.

So, while it's crashing inside libusb, that's because libpcap wasn't using libusb correctly.  If you've filed a libusb 
bug, you might want to close it.

This bug was fixed last year in

commit 9f8827ee41bbf24c7dc98d5f6ff3790756e378f4
Author: Guy Harris <guy () alum mit edu>
Date:   Mon Aug 6 15:25:30 2012 -0700

    Check whether libusb_init() succeeds, and give up if it doesn't.
    
    libusb_init() isn't guaranteed to succeed; it returns a (presumably)
    non-zero error on failure.  If it doesn't return 0, just give up - we
    presumably don't have a valid libusb_context pointer, which is probably
    what's causing crashes when we call libusb_get_device_list() on a system
    with no usbfs mounted.
    
    This fixes bug 3554749 in the tracker, and a bunch of upstream bugs.
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