vs2010: Fix implementation of strcasestr

A haystack which is shorter than the needle resulted in negative value for length_haystack which was forced to a very large unsigned value. The resulting buffer overflow while reading the haystack would crash text2image when it was called with a short font name. Signed-off-by: Stefan Weil <[email protected]>
tesseract-ocr · Aug 31, 2016 · 4708ea3 · 4708ea3
1 parent 2660647
commit 4708ea3
Showing 1 changed file with 8 additions and 3 deletions.
diff --git a/vs2010/port/strcasestr.cpp b/vs2010/port/strcasestr.cpp
@@ -49,9 +49,14 @@ char *strcasestr(const char *haystack, const char *needle) {
      return NULL;
 
    length_needle = strlen(needle);
-   length_haystack = strlen(haystack) - length_needle + 1;
+   length_haystack = strlen(haystack);
 
-   for (i = 0; i < length_haystack; i++)
+   if (length_haystack < length_needle)
+     return NULL;
+
+   length_haystack -= length_needle;
+
+   for (i = 0; i <= length_haystack; i++)
      {
         size_t j;
 
@@ -71,4 +76,4 @@ char *strcasestr(const char *haystack, const char *needle) {
      }
 
    return NULL;
-}
+}