scanutils: Fix illegal memory access

Format strings which contain "%*s" show this error in Valgrind: ==32503== Conditional jump or move depends on uninitialised value(s) ==32503== at 0x2B8BB0: tvfscanf(_IO_FILE*, char const*, __va_list_tag*) (scanutils.cpp:486) ==32503== by 0x2B825A: tfscanf(_IO_FILE*, char const*, ...) (scanutils.cpp:234) ==32503== by 0x272B01: read_unlv_file(STRING, int, int, BLOCK_LIST*) (blread.cpp:54) ==32503== by 0x1753CD: tesseract::Tesseract::SegmentPage(STRING const*, BLOCK_LIST*, tesseract::Tesseract*, OSResults*) (pagesegmain.cpp:115) ==32503== by 0x1363CD: tesseract::TessBaseAPI::FindLines() (baseapi.cpp:2291) ==32503== by 0x130CF1: tesseract::TessBaseAPI::Recognize(ETEXT_DESC*) (baseapi.cpp:802) ==32503== by 0x1322D3: tesseract::TessBaseAPI::ProcessPage(Pix*, int, char const*, char const*, int, tesseract::TessResultRenderer*) (baseapi.cpp:1176) ==32503== by 0x131A84: tesseract::TessBaseAPI::ProcessPagesMultipageTiff(unsigned char const*, unsigned long, char const*, char const*, int, tesseract::TessResultRenderer*, int) (baseapi.cpp:1013) ==32503== by 0x132052: tesseract::TessBaseAPI::ProcessPagesInternal(char const*, char const*, int, tesseract::TessResultRenderer*) (baseapi.cpp:1129) ==32503== by 0x131B1E: tesseract::TessBaseAPI::ProcessPages(char const*, char const*, int, tesseract::TessResultRenderer*) (baseapi.cpp:1032) ==32503== by 0x12E00C: main (tesseractmain.cpp:537) ==32503== Uninitialised value was created by a stack allocation ==32503== at 0x272A60: read_unlv_file(STRING, int, int, BLOCK_LIST*) (blread.cpp:41) Signed-off-by: Stefan Weil <[email protected]>
tesseract-ocr · Jun 8, 2018 · 280db06 · 280db06
1 parent a662306
commit 280db06
Showing 1 changed file with 4 additions and 3 deletions.
diff --git a/src/ccutil/scanutils.cpp b/src/ccutil/scanutils.cpp
@@ -472,8 +472,10 @@ static int tvfscanf(FILE* stream, const char *format, va_list ap) {
 
             case 's':               // String
             {
-              char *sp;
-              sp = sarg = va_arg(ap, char *);
+              if (!(flags & FL_SPLAT)) {
+                sarg = va_arg(ap, char *);
+              }
+              char *sp = sarg;
               while (width--) {
                 q = fgetc(stream);
                 if (isspace(static_cast<unsigned char>(q)) || q <= 0) {
@@ -488,7 +490,6 @@ static int tvfscanf(FILE* stream, const char *format, va_list ap) {
               } else if (!(flags & FL_SPLAT)) {
                 *sp = '\0'; // Terminate output
                 converted++;
-              } else {
               }
             }
             break;