Description of problem:
We provide extra software via a network mountpoint, and we were told in BZ#1353249 to add extra Gnome menus by defining $XDG_DATA_DIRS to include the location of the additional menus.  Because of license restrictions, not everyone can run this software, so not everyone has permission to see into the network share.  I've discovered that if one of the directories in $XDG_DATA_DIRS exists but does not permit users to read, gnome-shell will segfault, and you'll get the "Oh no!  Something has gone wrong." display where you can only log out. 

Version-Release number of selected component (if applicable):
gnome-shell-3.14.4-37.el7.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Create an inaccesible directory:  
mkdir -m 0700 /usr/inaccessible
mkdir -m 0700 /usr/inaccessible/dir

2. Add the inaccessible directory to XDG_DATADIRS:
echo 'export XDG_DATA_DIRS=${XDG_DATA_DIRS:-/usr/share:/usr/local/share}:/usr/inaccessible/dir' > /etc/X11/xinit/xinitrc.d/99-extraapps.sh

3.  Attempt to log in using gnome-shell or gnome-shell classic.

Actual results:
You will be presented with the Oh no! error message with the only option to log out.

Expected results:
Normal login, user won't be able to see any menus in /usr/inaccessible, but otherwise normal.

Additional info:
When gnome-shell's javascript interpreter is trying to import the 'gi' class, it delves into several directories.  

In the journal, I'm seeing:

Aug 10 11:08:34 caen-z240.engin.umich.edu gnome-session[13178]: (gnome-shell:13468): Gjs-WARNING **: JS ERROR: Error: No property 'gi' in importer (or its value was undefined)
Aug 10 11:08:34 caen-z240.engin.umich.edu gnome-session[13178]: @<main>:1
Aug 10 11:08:34 caen-z240.engin.umich.edu kernel: gnome-shell[13468]: segfault at 8 ip 00007f9baff143d0 sp 00007ffd698e51d8 error 4 in libmozjs-24.so[7f9bafd72000+562000]
Aug 10 11:08:34 caen-z240.engin.umich.edu gnome-session[13178]: WARNING: Application 'gnome-shell-classic.desktop' killed by signal 11
Aug 10 11:08:34 caen-z240.engin.umich.edu gnome-session[13178]: gnome-session[13178]: WARNING: Application 'gnome-shell-classic.desktop' killed by signal 11


When I attached 'strace' to gnome-shell when I logged in, I saw:


14612 open("/usr/share/gjs-1.0/__init__.js", O_RDONLY) = -1 ENOENT (No such file or directory)
14612 lstat("/usr/share/gjs-1.0/overrides", 0x7fffe16e8ac0) = -1 ENOENT (No such file or directory)
14612 open("/usr/local/share/gjs-1.0/__init__.js", O_RDONLY) = -1 ENOENT (No such file or directory)
14612 lstat("/usr/local/share/gjs-1.0/overrides", 0x7fffe16e8ac0) = -1 ENOENT (No such file or directory)
14612 open("/usr/inaccessible/dir/gjs-1.0/__init__.js", O_RDONLY) = -1 EACCES (Permission denied)
14612 write(2, "\n(gnome-shell:14612): Gjs-WARNING **: JS ERROR: Error: No property 'gi' in importer (or its value was undefined)\n@<main>:1\n\n", 124) = 124
14612 --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x8} ---

if I change the permissions on /usr/inaccessible/dir so it's readable (0755), I see:

18720 open("/usr/share/gjs-1.0/__init__.js", O_RDONLY) = -1 ENOENT (No such file or directory)
18720 lstat("/usr/share/gjs-1.0/overrides", 0x7ffedd4810a0) = -1 ENOENT (No such file or directory)
18720 open("/usr/local/share/gjs-1.0/__init__.js", O_RDONLY) = -1 ENOENT (No such file or directory)
18720 lstat("/usr/local/share/gjs-1.0/overrides", 0x7ffedd4810a0) = -1 ENOENT (No such file or directory)
18720 open("/usr/inaccessible/dir/gjs-1.0/__init__.js", O_RDONLY) = -1 ENOENT (No such file or directory)
18720 lstat("/usr/inaccessible/dir/gjs-1.0/overrides", 0x7ffedd4810a0) = -1 ENOENT (No such file or directory)
18720 open("/usr/share/gjs-1.0/__init__.js", O_RDONLY) = -1 ENOENT (No such file or directory)
18720 lstat("/usr/share/gjs-1.0/overrides", 0x7ffedd4810a0) = -1 ENOENT (No such file or directory)
18720 stat("libglib-2.0.so.0", 0x7ffedd480570) = -1 ENOENT (No such file or directory)
18720 stat("libglib-2.0.so.0.so", 0x7ffedd480570) = -1 ENOENT (No such file or directory)
18720 stat("libglib-2.0.so.0.la", 0x7ffedd480570) = -1 ENOENT (No such file or directory)
18720 stat("libgobject-2.0.so.0", 0x7ffedd480570) = -1 ENOENT (No such file or directory)
18720 stat("libgobject-2.0.so.0.so", 0x7ffedd480570) = -1 ENOENT (No such file or directory)
18720 stat("libgobject-2.0.so.0.la", 0x7ffedd480570) = -1 ENOENT (No such file or directory)
18720 futex(0x7f1a2c1b54a8, FUTEX_WAKE, 2147483647) = 0
18720 futex(0x7f1a2c1b54a8, FUTEX_WAKE, 2147483647) = 0
18720 open("/usr/lib64/gjs/girepository-1.0/Clutter-1.0.typelib", O_RDONLY) = -1 ENOENT (No such file or directory)
18720 open("/usr/lib64/gnome-shell/Clutter-1.0.typelib", O_RDONLY) = -1 ENOENT (No such file or directory)
18720 open("/usr/lib64/mutter/Clutter-1.0.typelib", O_RDONLY) = -1 ENOENT (No such file or directory)
18720 open("/usr/lib64/mutter/Clutter-1.0.typelib", O_RDONLY) = -1 ENOENT (No such file or directory)
18720 open("/usr/lib64/girepository-1.0/Clutter-1.0.typelib", O_RDONLY) = 22
18720 fstat(22, {st_mode=S_IFREG|0644, st_size=493400, ...}) = 0
18720 mmap(NULL, 493400, PROT_READ, MAP_PRIVATE, 22, 0) = 0x7f1a1405c000
18720 close(22)                         = 0

(and so on, it works)

The bug appears to be that gnome-shell's javascript engine (mozjs24) segfaults when it tries a directory and gets a EACCESS instead of ENOENT.