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[1/3] stdlib: Avoid another self-comparison in qsort

Message ID 58229f369d7bb3eb1883de9ba0ff2ad974853c5b.1700246487.git.fweimer@redhat.com
State New
Headers show
Series Various qsort fixes | expand

Commit Message

Florian Weimer Nov. 17, 2023, 6:44 p.m. UTC 
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.
---
 stdlib/qsort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Adhemerval Zanella Netto Nov. 20, 2023, 7:05 p.m. UTC | #1 
On 17/11/23 15:44, Florian Weimer wrote:
> 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.

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  stdlib/qsort.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/stdlib/qsort.c b/stdlib/qsort.c
> index ad110e8a89..6d0c4447ec 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 (run_ptr != tmp_ptr && cmp (run_ptr, tmp_ptr, arg) < 0)
>          tmp_ptr -= size;
>  
>        tmp_ptr += size;
diff mbox series

Patch

diff --git a/stdlib/qsort.c b/stdlib/qsort.c
index ad110e8a89..6d0c4447ec 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 (run_ptr != tmp_ptr && cmp (run_ptr, tmp_ptr, arg) < 0)
         tmp_ptr -= size;
 
       tmp_ptr += size;