#181 OSS-Fuzz ZBarcode_Encode_File fix, allow for zero-length file, free buffer on error

backend/library.c

@@ -1424,13 +1424,14 @@ int ZBarcode_Encode_and_Buffer_Vector(struct zint_symbol *symbol, unsigned char
 int ZBarcode_Encode_File(struct zint_symbol *symbol, char *filename) {
     FILE *file;
     unsigned char *buffer;
-    unsigned long fileLen;
+    long fileLen;
-    unsigned int nRead = 0, n = 0;
+    size_t n;
+    int nRead = 0;
     int ret;
 
     if (!strcmp(filename, "-")) {
         file = stdin;
-        fileLen = 7100;
+        fileLen = 7900;
     } else {
         file = fopen(filename, "rb");
         if (!file) {
@@ -1444,13 +1445,19 @@ int ZBarcode_Encode_File(struct zint_symbol *symbol, char *filename) {
         fileLen = ftell(file);
         fseek(file, 0, SEEK_SET);
 
-        if (fileLen > 7100) {
+        if (fileLen > 7900) {
-            /* The largest amount of data that can be encoded is 7089 numeric digits in QR Code */
+            /* The largest amount of data that can be encoded is 7827 numeric digits in Han Xin Code */
             strcpy(symbol->errtxt, "230: Input file too long");
             error_tag(symbol->errtxt, ZINT_ERROR_INVALID_DATA);
             fclose(file);
             return ZINT_ERROR_INVALID_DATA;
         }
+        if (fileLen <= 0) {
+            strcpy(symbol->errtxt, "235: Input file empty or unseekable");
+            error_tag(symbol->errtxt, ZINT_ERROR_INVALID_DATA);
+            fclose(file);
+            return ZINT_ERROR_INVALID_DATA;
+        }
     }
 
     /* Allocate memory */
@@ -1458,8 +1465,9 @@ int ZBarcode_Encode_File(struct zint_symbol *symbol, char *filename) {
     if (!buffer) {
         strcpy(symbol->errtxt, "231: Internal memory error");
         error_tag(symbol->errtxt, ZINT_ERROR_MEMORY);
-        if (strcmp(filename, "-"))
+        if (strcmp(filename, "-")) {
             fclose(file);
+        }
         return ZINT_ERROR_MEMORY;
     }
 
@@ -1469,12 +1477,18 @@ int ZBarcode_Encode_File(struct zint_symbol *symbol, char *filename) {
         n = fread(buffer + nRead, 1, fileLen - nRead, file);
         if (ferror(file)) {
             strcpy(symbol->errtxt, strerror(errno));
+            if (strcmp(filename, "-")) {
+                fclose(file);
+            }
+            free(buffer);
             return ZINT_ERROR_INVALID_DATA;
         }
         nRead += n;
     } while (!feof(file) && (0 < n) && (nRead < fileLen));
 
-    fclose(file);
+    if (strcmp(filename, "-")) {
+        fclose(file);
+    }
     ret = ZBarcode_Encode(symbol, buffer, nRead);
     free(buffer);
     return ret;

backend/tests/test_library.c

@@ -1,6 +1,6 @@
 /*
     libzint - the open source barcode library
-    Copyright (C) 2008-2019 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2008-2020 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -30,6 +30,9 @@
 /* vim: set ts=4 sw=4 et : */
 
 #include "testcommon.h"
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
 
 static void test_checks(void)
 {
@@ -143,10 +146,64 @@ static void test_input_mode(void)
     testFinish();
 }
 
+// #181 Nico Gunkel OSS-Fuzz
+static void test_encode_file_zero_length(void)
+{
+    testStart("");
+
+    int ret;
+    char filename[] = "in.bin";
+    int fd;
+
+    struct zint_symbol* symbol = ZBarcode_Create();
+    assert_nonnull(symbol, "Symbol not created\n");
+
+    (void)remove(filename); // In case junk hanging around
+    fd = creat(filename, S_IRUSR);
+    assert_nonzero(fd, "Input file not created\n");
+    assert_zero(close(fd), "close(%s) != 0\n", filename);
+
+    ret = ZBarcode_Encode_File(symbol, filename);
+    assert_equal(ret, ZINT_ERROR_INVALID_DATA, "ret %d != ZINT_ERROR_INVALID_DATA\n", ret);
+
+    assert_zero(remove(filename), "remove(%s) != 0\n", filename);
+
+    ZBarcode_Delete(symbol);
+
+    testFinish();
+}
+
+// #181 Nico Gunkel OSS-Fuzz (buffer not freed on fread() error) Note: unable to reproduce fread() error using this method
+static void test_encode_file_directory(void)
+{
+    testStart("");
+
+    int ret;
+    char dirname[] = "in_dir";
+    int fd;
+
+    struct zint_symbol* symbol = ZBarcode_Create();
+    assert_nonnull(symbol, "Symbol not created\n");
+
+    (void)rmdir(dirname); // In case junk hanging around
+    assert_zero(mkdir(dirname, 0700), "mkdir(%s, 0700) != 0\n", dirname);
+
+    ret = ZBarcode_Encode_File(symbol, dirname);
+    assert_equal(ret, ZINT_ERROR_INVALID_DATA, "ret %d != ZINT_ERROR_INVALID_DATA (%s)\n", ret, symbol->errtxt);
+
+    assert_zero(rmdir(dirname), "rmdir(%s) != 0\n", dirname);
+
+    ZBarcode_Delete(symbol);
+
+    testFinish();
+}
+
 int main()
 {
     test_checks();
     test_input_mode();
+    test_encode_file_zero_length();
+    test_encode_file_directory();
 
     testReport();