Fix overrun when comparing with unterminated ICU language string.

The overrun was introduced in commit c4ff35f10.

Author: Andreas Karlsson <andreas@proxel.se>
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/96d80a47-f17f-42fa-82b1-2908efbd6541@gmail.com
Backpatch-through: 18

diff --git a/src/backend/utils/adt/pg_locale_icu.c b/src/backend/utils/adt/pg_locale_icu.c
index 5ad05fcd01695109fca329832b469ce3254b4827..a4a4e82eb9e98ad730b9a4c0f6b2718207146598 100644 (file)
--- a/src/backend/utils/adt/pg_locale_icu.c
+++ b/src/backend/utils/adt/pg_locale_icu.c
@@ -989,11 +989,11 @@ static int32_t
 foldcase_options(const char *locale)
 {
        uint32          options = U_FOLD_CASE_DEFAULT;
-       char            lang[3];
+       char            lang[ULOC_LANG_CAPACITY];
        UErrorCode      status = U_ZERO_ERROR;
 
-       uloc_getLanguage(locale, lang, 3, &status);
-       if (U_SUCCESS(status))
+       uloc_getLanguage(locale, lang, ULOC_LANG_CAPACITY, &status);
+       if (U_SUCCESS(status) && status != U_STRING_NOT_TERMINATED_WARNING)
        {
                /*
                 * The option name is confusing, but it causes u_strFoldCase to use