I am also convinced that the bug is not inside the pcscd. It could be inside libifd-cyberjack6 or libusb. Please help investigating it.

The exact HW I am using is this device:

http://www.reiner-sct.com/produkte/chipkartenleser/cyberjack_secoder.html?pEl=2

To reproduce the bug let the device unconnecting and start the pcscd deamon with options "-d -f". Connect the device, disconnect the device and reconnect.

I compiled the source packages in order to investigate the bug a little deeper on my own. When the device is connected the first time a bunch of threads are spawned where 2 will last for longer time. The 2 mentioned threads have the IDs 5+6.

(gdb) info thr
  Id   Target Id         Frame 
  6    Thread 0x7ffff555d700 (LWP 19617) "pcscd" 0x00007ffff75aab9d in nanosleep () at ../sysdeps/unix/syscall-template.S:81
  5    Thread 0x7ffff5d5e700 (LWP 19616) "pcscd" 0x00007ffff72c2fbd in poll () at ../sysdeps/unix/syscall-template.S:81
  2    Thread 0x7ffff71d4700 (LWP 19581) "pcscd" 0x00007ffff72c7c33 in select () at ../sysdeps/unix/syscall-template.S:81
* 1    Thread 0x7ffff7fcf740 (LWP 19580) "pcscd" 0x00007ffff72c7c33 in select () at ../sysdeps/unix/syscall-template.S:81

Thead with ID 5 will cause the crash later on: Looking into the call stack show the following:

(gdb) thr 5
[Switching to thread 5 (Thread 0x7ffff5d5e700 (LWP 19616))]
#0  0x00007ffff72c2fbd in poll () at ../sysdeps/unix/syscall-template.S:81
81      ../sysdeps/unix/syscall-template.S: No such file or directory.
(gdb) bt
#0  0x00007ffff72c2fbd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007ffff658d248 in poll (__timeout=-1, __nfds=2, __fds=0x7ffff5d5def0) at /usr/include/x86_64-linux-gnu/bits/poll2.h:46
#2  linux_udev_event_thread_main (arg=<optimized out>) at ../../libusb/os/linux_udev.c:175
#3  0x00007ffff75a3182 in start_thread (arg=0x7ffff5d5e700) at pthread_create.c:312
#4  0x00007ffff72d030d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

When disconnecting the device the thread with ID5 is gone while the one with ID5 is still present but in a strange state.

info threads
  Id   Target Id         Frame 
  5    Thread 0x7ffff5d5e700 (LWP 19616) "pcscd" 0x00007ffff72c2fbd in poll () at ../sysdeps/unix/syscall-template.S:81
  2    Thread 0x7ffff71d4700 (LWP 19581) "pcscd" 0x00007ffff72c7c33 in select () at ../sysdeps/unix/syscall-template.S:81
* 1    Thread 0x7ffff7fcf740 (LWP 19580) "pcscd" 0x00007ffff72c7c33 in select () at ../sysdeps/unix/syscall-template.S:81
(gdb) thr 5
[Switching to thread 5 (Thread 0x7ffff5d5e700 (LWP 19616))]
#0  0x00007ffff72c2fbd in poll () at ../sysdeps/unix/syscall-template.S:81
81      ../sysdeps/unix/syscall-template.S: No such file or directory.
(gdb) bt
#0  0x00007ffff72c2fbd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007ffff658d248 in ?? ()
#2  0x00007ffff7590868 in __elf_set___libc_thread_subfreeres_element___rpc_thread_destroy__ ()
#3  0x00007ffff7590860 in __elf_set___libc_thread_subfreeres_element_res_thread_freeres__ () from /lib/x86_64-linux-gnu/libc.so.6
#4  0x0000000100000006 in ?? ()
#5  0x0000000100000005 in ?? ()
#6  0x00007ffff5d5e700 in ?? ()
#7  0x00007ffff5d5e700 in ?? ()
#8  0x0000000000000000 in ?? ()

The thread seems to be in destruction but is still waiting inside poll for something. Perhaps some hook (pthread_cleanup_push)? In Task List it has still an priority, so it's no zombie.

When I reconnect the device the pcscd crashed after some seconds. This is the stack trace:

 Program received signal SIGSEGV, Segmentation fault.
0x00007ffff658d248 in ?? ()
(gdb) bt
#0  0x00007ffff658d248 in ?? ()
#1  0x00007ffff7590868 in __elf_set___libc_thread_subfreeres_element___rpc_thread_destroy__ ()
#2  0x00007ffff7590860 in __elf_set___libc_thread_subfreeres_element_res_thread_freeres__ () from /lib/x86_64-linux-gnu/libc.so.6
#3  0x0000000100000006 in ?? ()
#4  0x0001000100000005 in ?? ()
#5  0x00007ffff5d5e700 in ?? ()
#6  0x00007ffff5d5e700 in ?? ()
#7  0x0000000000000000 in ?? ()
(gdb) info threads
  Id   Target Id         Frame 
* 5    Thread 0x7ffff5d5e700 (LWP 19616) "pcscd" 0x00007ffff658d248 in ?? ()
  2    Thread 0x7ffff71d4700 (LWP 19581) "pcscd" 0x00007ffff72c7c33 in select () at ../sysdeps/unix/syscall-template.S:81
  1    Thread 0x7ffff7fcf740 (LWP 19580) "pcscd" 0x00007ffff72c7c33 in select () at ../sysdeps/unix/syscall-template.S:81

The poll returned and while returning the segfault is beeing generated.

The thread itself stucks inside libusb. Perhaps the error is inside libusb. I have not the project knowledge to get deeper into it.