Segfault when accessing an Android device right after clicking "accept" on the Android device

Distribution

Debian unstable

Package version

6.2.8-1

Frequency

Always

Bug description

Hey.

(I think none of the other segfault issues already reported are the same one than this.)

This is a long standing bug (since years):

Steps to reproduce

1. I connect an Android device (it happens with all that I have, which use many different versions of Android) via USB
2. usbguard asks me the first time whether I want to allow the device to be accessed (which I accept).
3. I click on the tree-view item for the Android device in nemo.
4. Then the Android device itself displays the pop up where it asks me whether I want to allow or reject the connection.
5. Right when I accept that, nemo segfaults like so in the kernel log:

   Oct 30 16:30:28 heisenberg kernel: nemo[729399]: segfault at 18 ip 00005652b336bdd4 sp 00007ffcb89f9f28 error 4 in nemo[e7dd4,5652b32b5000+106000] likely on CPU 12 (core 20, socket 0)
   Oct 30 16:30:28 heisenberg kernel: Code: f6 e8 40 b6 f4 ff 48 89 df 5b e9 cf 12 f5 ff 0f 1f 80 00 00 00 00 c3 0f 1f 80 00 00 00 00 5b c3 66 0f 1f 44 00 00 f3 0f 1e fa <48> 8b 47 18 48 8b 10 48 8b 52 18 48 8b 3a 48 85 ff 74 09 48 8b 70
   

6. Along with that, the first USB device, which I've accepted with usbguard above is removed from the kernel and a new one appears, for which usbguard asks me again, whether I want to accept it (to the kernel) or not. I accept it.
7. If I then start a new nemo, I can click the Android device in that, and from then on it works (for that device and until I disconnect it).

Expected behavior

Don't crash the first time ;-)

Additional information

With debug symbols installed, I'd get the following backtrace right after the SIGSEV:

$ gdb nemo
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Reading symbols from nemo...
Reading symbols from /usr/lib/debug/.build-id/84/207c4babdfd219ac42df26ef030bc3007785a1.debug...
(gdb) run
Starting program: /usr/bin/nemo 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff32006c0 (LWP 729919)]
[New Thread 0x7ffff28006c0 (LWP 729920)]
[New Thread 0x7ffff1e006c0 (LWP 729921)]

(nemo:729916): Gtk-WARNING **: 16:33:13.510: Failed to register client: GDBus.Error:org.gnome.SessionManager.AlreadyRegistered: Unable to register client
[New Thread 0x7ffff14006c0 (LWP 729922)]
[New Thread 0x7ffff0a006c0 (LWP 729923)]

(nemo:729916): Nemo-WARNING **: 16:33:13.525: Current gtk theme is not known to have nemo support (Adwaita) - checking...

(nemo:729916): Nemo-WARNING **: 16:33:13.550: The theme appears to have no nemo support.  Adding some...
[New Thread 0x7fffeaa006c0 (LWP 729925)]
[New Thread 0x7fffe96006c0 (LWP 729926)]
[New Thread 0x7fffe8c006c0 (LWP 729927)]
[New Thread 0x7fffdf6006c0 (LWP 729928)]
[Thread 0x7fffe96006c0 (LWP 729926) exited]
[Thread 0x7ffff0a006c0 (LWP 729923) exited]
[Thread 0x7fffdf6006c0 (LWP 729928) exited]
[Thread 0x7fffe8c006c0 (LWP 729927) exited]
[New Thread 0x7fffe8c006c0 (LWP 729949)]
[New Thread 0x7fffdf6006c0 (LWP 729961)]
[Thread 0x7fffe8c006c0 (LWP 729949) exited]

Thread 1 "nemo" received signal SIGSEGV, Segmentation fault.
nemo_file_is_desktop_directory (file=file@entry=0x0) at ../libnemo-private/nemo-file.c:1482
warning: 1482	../libnemo-private/nemo-file.c: No such file or directory
(gdb) bt
#0  nemo_file_is_desktop_directory (file=file@entry=0x0) at ../libnemo-private/nemo-file.c:1482
#1  0x00005555555fcb6c in viewed_file_changed_callback (file=0x555555837f80, slot=0x555555b1fdc0) at ../src/nemo-window-manage-views.c:289
#2  0x00007ffff71cd9c0 in g_closure_invoke () from /lib/x86_64-linux-gnu/libgobject-2.0.so.0
#3  0x00007ffff71e1d83 in ?? () from /lib/x86_64-linux-gnu/libgobject-2.0.so.0
#4  0x00007ffff71e37a9 in ?? () from /lib/x86_64-linux-gnu/libgobject-2.0.so.0
#5  0x00007ffff71e9666 in g_signal_emit_valist () from /lib/x86_64-linux-gnu/libgobject-2.0.so.0
#6  0x00007ffff71e9723 in g_signal_emit () from /lib/x86_64-linux-gnu/libgobject-2.0.so.0
#7  0x0000555555645077 in nemo_file_emit_changed (file=0x555555837f80) at ../libnemo-private/nemo-file.c:7953
#8  0x0000555555622708 in nemo_directory_emit_change_signals (directory=0x5555561a73a0, changed_files=0x555555c06b70) at ../libnemo-private/nemo-directory.c:776
#9  0x0000555555622a19 in call_files_changed_common (directory=<optimized out>, file_list=<optimized out>) at ../libnemo-private/nemo-directory.c:870
#10 call_files_changed_unref_free_list (key=0x5555561a73a0, value=0x555555c06b70, user_data=<optimized out>) at ../libnemo-private/nemo-directory.c:889
#11 0x00007ffff70b1cd3 in g_hash_table_foreach () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#12 0x0000555555622f09 in nemo_directory_notify_files_removed (files=<optimized out>) at ../libnemo-private/nemo-directory.c:1158
#13 0x000055555567548d in nemo_file_changes_consume_changes (consume_all=consume_all@entry=1) at ../libnemo-private/nemo-file-changes-queue.c:314
#14 0x0000555555661c02 in call_consume_changes_idle_cb (not_used=<optimized out>) at ../libnemo-private/nemo-monitor.c:69
#15 0x00007ffff70c37df in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#16 0x00007ffff70c5a17 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#17 0x00007ffff70c6180 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#18 0x00007ffff7303445 in g_application_run () from /lib/x86_64-linux-gnu/libgio-2.0.so.0
#19 0x000055555558d186 in main (argc=1, argv=0x7fffffffdf88) at ../src/nemo-main.c:104
(gdb) 

(That's not from the same run, as for which the kernel log message was generated, that I've cited above.)

In terms of kernel log, it looks like that:

Connecting the device:

Oct 30 16:45:59 heisenberg kernel: usb 4-1: new SuperSpeed USB device number 28 using xhci_hcd
Oct 30 16:45:59 heisenberg kernel: usb 4-1: New USB device found, idVendor=04e8, idProduct=6860, bcdDevice= c.00
Oct 30 16:45:59 heisenberg kernel: usb 4-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Oct 30 16:45:59 heisenberg kernel: usb 4-1: Product: SAMSUNG_Android
Oct 30 16:45:59 heisenberg kernel: usb 4-1: Manufacturer: SAMSUNG
Oct 30 16:45:59 heisenberg kernel: usb 4-1: SerialNumber: R3CN4013TZY
Oct 30 16:45:59 heisenberg kernel: usb 4-1: Device is not authorized for usage

next I accept it in usbguard:
Oct 30 16:46:21 heisenberg kernel: cdc_acm 4-1:1.1: ttyACM0: USB ACM device
Oct 30 16:46:21 heisenberg kernel: usb 4-1: authorized to connect

next I click on it within `nemo`, Android itself asks me whether I want to accept, which I do, and right after I get:

Oct 30 16:46:30 heisenberg kernel: usb 4-1: USB disconnect, device number 28
Oct 30 16:46:30 heisenberg kernel: nemo[730999]: segfault at 18 ip 00005617ca4dadd4 sp 00007ffee1fa7508 error 4 in nemo[e7dd4,5617ca424000+106000] likely on CPU 15 (core 23, socket 0)
Oct 30 16:46:30 heisenberg kernel: Code: f6 e8 40 b6 f4 ff 48 89 df 5b e9 cf 12 f5 ff 0f 1f 80 00 00 00 00 c3 0f 1f 80 00 00 00 00 5b c3 66 0f 1f 44 00 00 f3 0f 1e fa <48> 8b 47 18 48 8b 10 48 8b 52 18 48 8b 3a 48 85 ff 74 09 48 8b 70
Oct 30 16:46:31 heisenberg kernel: usb 4-1: new SuperSpeed USB device number 29 using xhci_hcd
Oct 30 16:46:31 heisenberg kernel: usb 4-1: New USB device found, idVendor=04e8, idProduct=6860, bcdDevice= c.00
Oct 30 16:46:31 heisenberg kernel: usb 4-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Oct 30 16:46:31 heisenberg kernel: usb 4-1: Product: SAMSUNG_Android
Oct 30 16:46:31 heisenberg kernel: usb 4-1: Manufacturer: SAMSUNG
Oct 30 16:46:31 heisenberg kernel: usb 4-1: SerialNumber: R3CN4013TZY
Oct 30 16:46:31 heisenberg kernel: usb 4-1: Device is not authorized for usage

`usbguard` asks me for the "new" device (which I accept):

Oct 30 16:46:35 heisenberg kernel: cdc_acm 4-1:1.1: ttyACM0: USB ACM device
Oct 30 16:46:35 heisenberg kernel: usb 4-1: authorized to connect

here I can now restart `nemo` and actually use the device until I'd disconnect it.

Oct 30 16:46:39 heisenberg kernel: usb 4-1: USB disconnect, device number 29

Thanks,
Chris.

Reproduce the USB authorization sequence, then inspect viewed_file_changed_callback in src/nemo-window-manage-views.c and nemo_file_is_desktop_directory in libnemo-private/nemo-file.c using the supplied GDB backtrace. Follow the file-removal path through nemo-directory.c, nemo-file-changes-queue.c, and nemo-monitor.c. Done means accepting the Android connection no longer crashes nemo.