Here's what my user who found this problem, says:

fyi
More info for if those gsl guys start a discussion:

1.) ./a.out 128 128 or 256 256 or 512 512 or 1024 1024 does not crash,
    so you don't always get the fault.

2.) The problem might be the status of a singular matrix:

status = LU_decomp_L3 (&AL.matrix, ipiv);

If not singular then status = 0 and all fields of vector ipiv are valid(have been processed).

if singular then status = number of fields which have been processed.

For example: singular 127x127 status = 16
means that this is wrong:
for (i = 0; i < minMN; ++i) {  # the segfault area

Better is this:
size_t damage = minMN;
if (status) damage = status;
for (i = 0; i < damage; ++i) {
} 

Even better (perhaps)
if (status)  { ; /* singular, do nothing */
} else {
   for (i = 0; i < minMN; ++i) {
   :
}
gsl_vector_uint_free(ipiv);
return status;

Performance back: no calloc and in case of singular dismiss signum as valueless.

### Set to 0

$ rm a.out
~/tools/gsl/gsl-release-2-8  $ gcc -I$HOME/tools/gsl/gsl-release-2-8 ~/trealla/x.c -L$HOME/tools/gsl/gsl-release-2-8/.libs -L$HOME/tools/gsl/gsl-release-2-8/cblas/.libs -lgsl -lgslcblas -lm
~/tools/gsl/gsl-release-2-8  $ ./a.out 127 127
v2.8 127x127
-0.000000

### NOW change to 1

~/tools/gsl/gsl-release-2-8  $ gcc -I$HOME/tools/gsl/gsl-release-2-8 ~/trealla/x.c -L$HOME/tools/gsl/gsl-release-2-8/.libs -L$HOME/tools/gsl/gsl-release-2-8/cblas/.libs -lgsl -lgslcblas -lm
~/tools/gsl/gsl-release-2-8  $ ./a.out 127 127
v2.8 127x127
Segmentation fault (core dumped)
~/tools/gsl/gsl-release-2-8  $


(file #56320)