[PATCH v2] locale: Fix localedata/sort-test undefined behavior

[PATCH v2] locale: Fix localedata/sort-test undefined behavior

[Adhemerval Zanella]

The collate-test.c triggers UB with an signed integer overflow,
which results in an error on some architectures (powerpc32).

Checked on x86_64, i686, and powerpc.
---
 localedata/collate-test.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/localedata/collate-test.c b/localedata/collate-test.c
index 46b91ec57f..e6ca7e8e8b 100644
--- a/localedata/collate-test.c
+++ b/localedata/collate-test.c
@@ -32,6 +32,11 @@ struct lines
 
 static int xstrcoll (const void *, const void *);
 
+static int signum (int n)
+{
+  return (0 < n) - (n < 0);
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -86,7 +91,7 @@ main (int argc, char *argv[])
   srandom (atoi (argv[1]));
   for (n = 0; n < 10 * nstrings; ++n)
     {
-      int r1, r2, r;
+      int r1, r2;
       size_t idx1 = random () % nstrings;
       size_t idx2 = random () % nstrings;
       struct lines tmp = strings[idx1];
@@ -96,9 +101,8 @@ main (int argc, char *argv[])
       /* While we are at it a first little test.  */
       r1 = strcoll (strings[idx1].key, strings[idx2].key);
       r2 = strcoll (strings[idx2].key, strings[idx1].key);
-      r = r1 * r2;
 
-      if (r > 0 || (r == 0 && r1 != 0) || (r == 0 && r2 != 0))
+      if (signum (r1) != - signum (r2))
 	printf ("`%s' and `%s' collate wrong: %d vs. %d\n",
 		strings[idx1].key, strings[idx2].key, r1, r2);
     }
-- 
2.32.0

Re: [PATCH v2] locale: Fix localedata/sort-test undefined behavior

[H.J. Lu]

On Thu, Nov 4, 2021 at 6:01 AM Adhemerval Zanella via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> The collate-test.c triggers UB with an signed integer overflow,
> which results in an error on some architectures (powerpc32).
>
> Checked on x86_64, i686, and powerpc.
> ---
>  localedata/collate-test.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/localedata/collate-test.c b/localedata/collate-test.c
> index 46b91ec57f..e6ca7e8e8b 100644
> --- a/localedata/collate-test.c
> +++ b/localedata/collate-test.c
> @@ -32,6 +32,11 @@ struct lines
>
>  static int xstrcoll (const void *, const void *);
>
> +static int signum (int n)

signum on a separate line?

> +{
> +  return (0 < n) - (n < 0);
> +}
> +
>  int
>  main (int argc, char *argv[])
>  {
> @@ -86,7 +91,7 @@ main (int argc, char *argv[])
>    srandom (atoi (argv[1]));
>    for (n = 0; n < 10 * nstrings; ++n)
>      {
> -      int r1, r2, r;
> +      int r1, r2;
>        size_t idx1 = random () % nstrings;
>        size_t idx2 = random () % nstrings;
>        struct lines tmp = strings[idx1];
> @@ -96,9 +101,8 @@ main (int argc, char *argv[])
>        /* While we are at it a first little test.  */
>        r1 = strcoll (strings[idx1].key, strings[idx2].key);
>        r2 = strcoll (strings[idx2].key, strings[idx1].key);
> -      r = r1 * r2;
>
> -      if (r > 0 || (r == 0 && r1 != 0) || (r == 0 && r2 != 0))
> +      if (signum (r1) != - signum (r2))
>         printf ("`%s' and `%s' collate wrong: %d vs. %d\n",
>                 strings[idx1].key, strings[idx2].key, r1, r2);
>      }
> --
> 2.32.0
>


-- 
H.J.