[PATCH] stdlib: Avoid another self-comparison in qsort

[Florian Weimer <fweimer@redhat.com>]

In the insertion phase, we could run off the start of the array if the
comparison function never runs zero.  In that case, it never finds the
initial element that terminates the iteration.

Tested on i686-linux-gnu and x86_64-linux-gnu.

---
 stdlib/qsort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stdlib/qsort.c b/stdlib/qsort.c
index ad110e8a89..1ea31ff424 100644
--- a/stdlib/qsort.c
+++ b/stdlib/qsort.c
@@ -217,7 +217,7 @@ insertion_sort_qsort_partitions (void *const pbase, size_t total_elems,
   while ((run_ptr += size) <= end_ptr)
     {
       tmp_ptr = run_ptr - size;
-      while (cmp (run_ptr, tmp_ptr, arg) < 0)
+      while (tmp_ptr != base_ptr && cmp (run_ptr, tmp_ptr, arg) < 0)
         tmp_ptr -= size;
 
       tmp_ptr += size;

base-commit: 323f367cc46b80224d39b082adf7be74b49ed843