Paul Eggert wrote:
> I don't see the problem on cfarm220.cfarm.net with the current coreutils

That's because you are not on the /dev/wd0a disk on that machine.

What I see by single-stepping through "ls -Z ." in gdb is:
1. f->scontext gets set to "?".
2. Upon the first entry to function file_has_aclinfo_cache,
   all 4 variables
     static int unsupported_return;
     static char *unsupported_scontext;
     static int unsupported_scontext_err;
     static dev_t unsupported_device;
   are 0 or NULL, respectively. (As expected, since it's the first call
   to this function.)
   f->stat.st_dev is 0 (since "." is on the /dev/wd0a disk and this device
   has major and minor number both 0).
   Thus the condition (f->stat_ok && f->stat.st_dev == unsupported_device)
   evaluates to true, and four lines later, in
     ai->scontext = unsupported_scontext;
   an scontext gets set to NULL.

The fix is obviously to ignore these 4 static variables if they have not
been initialized. Done through the attached patch, which fixes the crash.