Fixed bug 3760 - RWops doesn't check for integer overflow when stdio_fseek only supports 32 bits

Simon Hug

When RWops seeks with fseek or fseeko it uses the types long or off_t which can be 32 bits on some platforms. stdio_seek does not check if the 64-bit integer for the offset fits into a 32-bit integer. Offsets equal or larger than 2 GiB will have implementation-defined behavior and failure states would be very confusing to debug.

The attached patch adds range checking by using the macros from limits.h for long type and some bit shifting for off_t because POSIX couldn't be bothered to specify min and max macros.

It also defines HAVE_FSEEKI64 in SDL_config_windows.h so that the Windows function gets picked up automatically with the default config.

And there's an additional error message for when ftell fails.

CMakeLists.txt

@@ -622,7 +622,7 @@ endif()
 if(LIBC)
   if(WINDOWS AND NOT MINGW)
     set(HAVE_LIBC TRUE)
-    foreach(_HEADER stdio.h string.h wchar.h ctype.h math.h)
+    foreach(_HEADER stdio.h string.h wchar.h ctype.h math.h limits.h)
       string(TOUPPER "HAVE_${_HEADER}" _UPPER)
       string(REPLACE "." "_" _HAVE_H ${_UPPER})
       set(${_HAVE_H} 1)
@@ -648,7 +648,7 @@ if(LIBC)
     set(HAVE_LIBC TRUE)
     check_include_file(sys/types.h HAVE_SYS_TYPES_H)
     foreach(_HEADER
-            stdio.h stdlib.h stddef.h stdarg.h malloc.h memory.h string.h
+            stdio.h stdlib.h stddef.h stdarg.h malloc.h memory.h string.h limits.h
             strings.h wchar.h inttypes.h stdint.h ctype.h math.h iconv.h signal.h)
       string(TOUPPER "HAVE_${_HEADER}" _UPPER)
       string(REPLACE "." "_" _HAVE_H ${_UPPER})

configure

@@ -16171,7 +16171,7 @@ $as_echo "#define STDC_HEADERS 1" >>confdefs.h
 
 fi
 
-    for ac_header in sys/types.h stdio.h stdlib.h stddef.h stdarg.h malloc.h memory.h string.h strings.h wchar.h inttypes.h stdint.h ctype.h math.h float.h iconv.h signal.h
+    for ac_header in sys/types.h stdio.h stdlib.h stddef.h stdarg.h malloc.h memory.h string.h strings.h wchar.h inttypes.h stdint.h limits.h ctype.h math.h float.h iconv.h signal.h
 do :
   as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
 ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"

configure.in

@@ -234,7 +234,7 @@ if test x$enable_libc = xyes; then
 
     dnl Check for C library headers
     AC_HEADER_STDC
-    AC_CHECK_HEADERS(sys/types.h stdio.h stdlib.h stddef.h stdarg.h malloc.h memory.h string.h strings.h wchar.h inttypes.h stdint.h ctype.h math.h float.h iconv.h signal.h)
+    AC_CHECK_HEADERS(sys/types.h stdio.h stdlib.h stddef.h stdarg.h malloc.h memory.h string.h strings.h wchar.h inttypes.h stdint.h limits.h ctype.h math.h float.h iconv.h signal.h)
 
     dnl Check for typedefs, structures, etc.
     AC_TYPE_SIZE_T

include/SDL_config.h.cmake

@@ -52,24 +52,25 @@
 #if HAVE_LIBC
 
 /* Useful headers */
-#cmakedefine HAVE_ALLOCA_H 1
-#cmakedefine HAVE_SYS_TYPES_H 1
-#cmakedefine HAVE_STDIO_H 1
 #cmakedefine STDC_HEADERS 1
-#cmakedefine HAVE_STDLIB_H 1
+#cmakedefine HAVE_ALLOCA_H 1
-#cmakedefine HAVE_STDARG_H 1
-#cmakedefine HAVE_MALLOC_H 1
-#cmakedefine HAVE_MEMORY_H 1
-#cmakedefine HAVE_STRING_H 1
-#cmakedefine HAVE_STRINGS_H 1
-#cmakedefine HAVE_WCHAR_H 1
-#cmakedefine HAVE_INTTYPES_H 1
-#cmakedefine HAVE_STDINT_H 1
 #cmakedefine HAVE_CTYPE_H 1
-#cmakedefine HAVE_MATH_H 1
 #cmakedefine HAVE_FLOAT_H 1
 #cmakedefine HAVE_ICONV_H 1
+#cmakedefine HAVE_INTTYPES_H 1
+#cmakedefine HAVE_LIMITS_H 1
+#cmakedefine HAVE_MALLOC_H 1
+#cmakedefine HAVE_MATH_H 1
+#cmakedefine HAVE_MEMORY_H 1
 #cmakedefine HAVE_SIGNAL_H 1
+#cmakedefine HAVE_STDARG_H 1
+#cmakedefine HAVE_STDINT_H 1
+#cmakedefine HAVE_STDIO_H 1
+#cmakedefine HAVE_STDLIB_H 1
+#cmakedefine HAVE_STRINGS_H 1
+#cmakedefine HAVE_STRING_H 1
+#cmakedefine HAVE_SYS_TYPES_H 1
+#cmakedefine HAVE_WCHAR_H 1
 #cmakedefine HAVE_PTHREAD_NP_H 1
 
 /* C library functions */

include/SDL_config.h.in

@@ -55,24 +55,25 @@
 #if HAVE_LIBC
 
 /* Useful headers */
-#undef HAVE_ALLOCA_H
-#undef HAVE_SYS_TYPES_H
-#undef HAVE_STDIO_H
 #undef STDC_HEADERS
-#undef HAVE_STDLIB_H
+#undef HAVE_ALLOCA_H
-#undef HAVE_STDARG_H
-#undef HAVE_MALLOC_H
-#undef HAVE_MEMORY_H
-#undef HAVE_STRING_H
-#undef HAVE_STRINGS_H
-#undef HAVE_WCHAR_H
-#undef HAVE_INTTYPES_H
-#undef HAVE_STDINT_H
 #undef HAVE_CTYPE_H
-#undef HAVE_MATH_H
 #undef HAVE_FLOAT_H
 #undef HAVE_ICONV_H
+#undef HAVE_INTTYPES_H
+#undef HAVE_LIMITS_H
+#undef HAVE_MALLOC_H
+#undef HAVE_MATH_H
+#undef HAVE_MEMORY_H
 #undef HAVE_SIGNAL_H
+#undef HAVE_STDARG_H
+#undef HAVE_STDINT_H
+#undef HAVE_STDIO_H
+#undef HAVE_STDLIB_H
+#undef HAVE_STRINGS_H
+#undef HAVE_STRING_H
+#undef HAVE_SYS_TYPES_H
+#undef HAVE_WCHAR_H
 #undef HAVE_PTHREAD_NP_H
 
 /* C library functions */

include/SDL_config_android.h

@@ -35,16 +35,17 @@
 
 #define HAVE_GCC_ATOMICS    1
 
-#define HAVE_ALLOCA_H       1
-#define HAVE_SYS_TYPES_H    1
-#define HAVE_STDIO_H    1
 #define STDC_HEADERS    1
-#define HAVE_STRING_H   1
+#define HAVE_ALLOCA_H       1
-#define HAVE_INTTYPES_H 1
-#define HAVE_STDINT_H   1
 #define HAVE_CTYPE_H    1
+#define HAVE_INTTYPES_H 1
+#define HAVE_LIMITS_H   1
 #define HAVE_MATH_H 1
 #define HAVE_SIGNAL_H 1
+#define HAVE_STDINT_H   1
+#define HAVE_STDIO_H    1
+#define HAVE_STRING_H   1
+#define HAVE_SYS_TYPES_H    1
 
 /* C library functions */
 #define HAVE_MALLOC 1

include/SDL_config_iphoneos.h

@@ -33,16 +33,17 @@
 
 #define HAVE_GCC_ATOMICS    1
 
-#define HAVE_ALLOCA_H       1
-#define HAVE_SYS_TYPES_H    1
-#define HAVE_STDIO_H    1
 #define STDC_HEADERS    1
-#define HAVE_STRING_H   1
+#define HAVE_ALLOCA_H       1
-#define HAVE_INTTYPES_H 1
-#define HAVE_STDINT_H   1
 #define HAVE_CTYPE_H    1
+#define HAVE_INTTYPES_H 1
+#define HAVE_LIMITS_H   1
 #define HAVE_MATH_H 1
 #define HAVE_SIGNAL_H   1
+#define HAVE_STDINT_H   1
+#define HAVE_STDIO_H    1
+#define HAVE_STRING_H   1
+#define HAVE_SYS_TYPES_H    1
 
 /* C library functions */
 #define HAVE_MALLOC 1

include/SDL_config_macosx.h

@@ -37,17 +37,18 @@
 #endif
 
 /* Useful headers */
-#define HAVE_ALLOCA_H       1
-#define HAVE_SYS_TYPES_H    1
-#define HAVE_STDIO_H    1
 #define STDC_HEADERS    1
-#define HAVE_STRING_H   1
+#define HAVE_ALLOCA_H       1
-#define HAVE_INTTYPES_H 1
-#define HAVE_STDINT_H   1
 #define HAVE_CTYPE_H    1
-#define HAVE_MATH_H 1
 #define HAVE_FLOAT_H    1
+#define HAVE_INTTYPES_H 1
+#define HAVE_LIMITS_H   1
+#define HAVE_MATH_H 1
 #define HAVE_SIGNAL_H   1
+#define HAVE_STDINT_H   1
+#define HAVE_STDIO_H    1
+#define HAVE_STRING_H   1
+#define HAVE_SYS_TYPES_H    1
 
 /* C library functions */
 #define HAVE_MALLOC 1

include/SDL_config_pandora.h

@@ -36,22 +36,24 @@
 
 #define SDL_BYTEORDER 1234
 
-#define HAVE_ALLOCA_H 1
-#define HAVE_SYS_TYPES_H 1
-#define HAVE_STDIO_H 1
 #define STDC_HEADERS 1
-#define HAVE_STDLIB_H 1
+#define HAVE_ALLOCA_H 1
-#define HAVE_STDARG_H 1
-#define HAVE_MALLOC_H 1
-#define HAVE_MEMORY_H 1
-#define HAVE_STRING_H 1
-#define HAVE_STRINGS_H 1
-#define HAVE_INTTYPES_H 1
-#define HAVE_STDINT_H 1
 #define HAVE_CTYPE_H 1
-#define HAVE_MATH_H 1
 #define HAVE_ICONV_H 1
+#define HAVE_INTTYPES_H 1
+#define HAVE_LIMITS_H 1
+#define HAVE_MALLOC_H 1
+#define HAVE_MATH_H 1
+#define HAVE_MEMORY_H 1
 #define HAVE_SIGNAL_H 1
+#define HAVE_STDARG_H 1
+#define HAVE_STDINT_H 1
+#define HAVE_STDIO_H 1
+#define HAVE_STDLIB_H 1
+#define HAVE_STRINGS_H 1
+#define HAVE_STRING_H 1
+#define HAVE_SYS_TYPES_H 1
+
 #define HAVE_MALLOC 1
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC 1

include/SDL_config_psp.h

@@ -33,16 +33,17 @@
 
 #define HAVE_GCC_ATOMICS    1
 
-#define HAVE_ALLOCA_H       1
-#define HAVE_SYS_TYPES_H    1
-#define HAVE_STDIO_H    1
 #define STDC_HEADERS    1
-#define HAVE_STRING_H   1
+#define HAVE_ALLOCA_H       1
-#define HAVE_INTTYPES_H 1
-#define HAVE_STDINT_H   1
 #define HAVE_CTYPE_H    1
+#define HAVE_INTTYPES_H 1
+#define HAVE_LIMITS_H   1
 #define HAVE_MATH_H 1
 #define HAVE_SIGNAL_H   1
+#define HAVE_STDINT_H   1
+#define HAVE_STDIO_H    1
+#define HAVE_STRING_H   1
+#define HAVE_SYS_TYPES_H    1
 
 /* C library functions */
 #define HAVE_MALLOC 1

include/SDL_config_windows.h

@@ -86,13 +86,14 @@ typedef unsigned int uintptr_t;
 /* This is disabled by default to avoid C runtime dependencies and manifest requirements */
 #ifdef HAVE_LIBC
 /* Useful headers */
-#define HAVE_STDIO_H 1
 #define STDC_HEADERS 1
-#define HAVE_STRING_H 1
 #define HAVE_CTYPE_H 1
-#define HAVE_MATH_H 1
 #define HAVE_FLOAT_H 1
+#define HAVE_LIMITS_H 1
+#define HAVE_MATH_H 1
 #define HAVE_SIGNAL_H 1
+#define HAVE_STDIO_H 1
+#define HAVE_STRING_H 1
 
 /* C library functions */
 #define HAVE_MALLOC 1
@@ -141,12 +142,19 @@ typedef unsigned int uintptr_t;
 #define HAVE_SQRTF 1
 #define HAVE_TAN 1
 #define HAVE_TANF 1
+#if defined(_MSC_VER)
+/* These functions were added with the VC++ 2013 C runtime library */
 #if _MSC_VER >= 1800
 #define HAVE_STRTOLL 1
 #define HAVE_VSSCANF 1
 #define HAVE_COPYSIGN 1
 #define HAVE_SCALBN 1
 #endif
+/* This function is available with at least the VC++ 2008 C runtime library */
+#if _MSC_VER >= 1400
+#define HAVE__FSEEKI64 1
+#endif
+#endif
 #if !defined(_MSC_VER) || defined(_USE_MATH_DEFINES)
 #define HAVE_M_PI 1
 #endif

include/SDL_config_winrt.h

@@ -98,13 +98,14 @@ typedef unsigned int uintptr_t;
 #define HAVE_XINPUT_H 1
 #endif
 #define HAVE_LIBC 1
-#define HAVE_STDIO_H 1
 #define STDC_HEADERS 1
-#define HAVE_STRING_H 1
 #define HAVE_CTYPE_H 1
-#define HAVE_MATH_H 1
 #define HAVE_FLOAT_H 1
+#define HAVE_LIMITS_H 1
+#define HAVE_MATH_H 1
 #define HAVE_SIGNAL_H 1
+#define HAVE_STDIO_H 1
+#define HAVE_STRING_H 1
 
 /* C library functions */
 #define HAVE_MALLOC 1

include/SDL_config_wiz.h

@@ -30,22 +30,24 @@
 
 #define SDL_BYTEORDER 1234
 
-#define HAVE_ALLOCA_H 1
-#define HAVE_SYS_TYPES_H 1
-#define HAVE_STDIO_H 1
 #define STDC_HEADERS 1
-#define HAVE_STDLIB_H 1
+#define HAVE_ALLOCA_H 1
-#define HAVE_STDARG_H 1
-#define HAVE_MALLOC_H 1
-#define HAVE_MEMORY_H 1
-#define HAVE_STRING_H 1
-#define HAVE_STRINGS_H 1
-#define HAVE_INTTYPES_H 1
-#define HAVE_STDINT_H 1
 #define HAVE_CTYPE_H 1
-#define HAVE_MATH_H 1
 #define HAVE_ICONV_H 1
+#define HAVE_INTTYPES_H 1
+#define HAVE_LIMITS_H 1
+#define HAVE_MALLOC_H 1
+#define HAVE_MATH_H 1
+#define HAVE_MEMORY_H 1
 #define HAVE_SIGNAL_H 1
+#define HAVE_STDARG_H 1
+#define HAVE_STDINT_H 1
+#define HAVE_STDIO_H 1
+#define HAVE_STDLIB_H 1
+#define HAVE_STRINGS_H 1
+#define HAVE_STRING_H 1
+#define HAVE_SYS_TYPES_H 1
+
 #define HAVE_MALLOC 1
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC 1

src/file/SDL_rwops.c

@@ -32,6 +32,13 @@
 #include "../core/windows/SDL_windows.h"
 #endif
 
+#ifdef HAVE_STDIO_H
+#include <stdio.h>
+#endif
+
+#ifdef HAVE_LIMITS_H
+#include <limits.h>
+#endif
 
 /* This file provides a general interface for SDL to read and write
    data sources.  It can easily be extended to files, memory, etc.
@@ -306,6 +313,19 @@ windows_file_close(SDL_RWops * context)
 #define fseek   fseeko64
 #define ftell   ftello64
 #elif defined(HAVE_FSEEKO)
+#if defined(OFF_MIN) && defined(OFF_MAX)
+#define FSEEK_OFF_MIN OFF_MIN
+#define FSEEK_OFF_MAX OFF_MAX
+#elif defined(HAVE_LIMITS_H)
+/* POSIX doesn't specify the minimum and maximum macros for off_t so
+ * we have to improvise and dance around implementation-defined
+ * behavior. This may fail if the off_t type has padding bits or
+ * is not a two's-complement representation. The compilers will detect
+ * and eliminate the dead code if off_t has 64 bits.
+ */
+#define FSEEK_OFF_MAX (((((off_t)1 << (sizeof(off_t) * CHAR_BIT - 2)) - 1) << 1) + 1)
+#define FSEEK_OFF_MIN (-(FSEEK_OFF_MAX) - 1)
+#endif
 #define fseek_off_t off_t
 #define fseek   fseeko
 #define ftell   ftello
@@ -314,6 +334,10 @@ windows_file_close(SDL_RWops * context)
 #define fseek   _fseeki64
 #define ftell   _ftelli64
 #else
+#ifdef HAVE_LIMITS_H
+#define FSEEK_OFF_MIN LONG_MIN
+#define FSEEK_OFF_MAX LONG_MAX
+#endif
 #define fseek_off_t long
 #endif
 
@@ -337,8 +361,18 @@ stdio_size(SDL_RWops * context)
 static Sint64 SDLCALL
 stdio_seek(SDL_RWops * context, Sint64 offset, int whence)
 {
+#if defined(FSEEK_OFF_MIN) && defined(FSEEK_OFF_MAX)
+    if (offset < (Sint64)(FSEEK_OFF_MIN) || offset > (Sint64)(FSEEK_OFF_MAX)) {
+        return SDL_SetError("Seek offset out of range");
+    }
+#endif
+
     if (fseek(context->hidden.stdio.fp, (fseek_off_t)offset, whence) == 0) {
-        return ftell(context->hidden.stdio.fp);
+        Sint64 pos = ftell(context->hidden.stdio.fp);
+        if (pos < 0) {
+            return SDL_SetError("Couldn't get stream offset");
+        }
+        return pos;
     }
     return SDL_Error(SDL_EFSEEK);
 }