convertbmp: detect invalid file dimensions early

width/length dimensions read from bmp headers are not necessarily
valid. For instance they may have been maliciously set to very large
values with the intention to cause DoS (large memory allocation, stack
overflow). In these cases we want to detect the invalid size as early
as possible.

This commit introduces a counter which verifies that the number of
written bytes corresponds to the advertized width/length.

Fixes #1059 (CVE-2018-6616).

diff --git a/src/bin/jp2/convertbmp.c b/src/bin/jp2/convertbmp.c
index 85a47feaf3b986684b531a45bda50a0bb5e6ba3a..0af52f816ba50ddb3e1e7ff9929b90f8a199643d 100644 (file)
--- a/src/bin/jp2/convertbmp.c
+++ b/src/bin/jp2/convertbmp.c
@@ -534,14 +534,14 @@ static OPJ_BOOL bmp_read_raw_data(FILE* IN, OPJ_UINT8* pData, OPJ_UINT32 stride,
 static OPJ_BOOL bmp_read_rle8_data(FILE* IN, OPJ_UINT8* pData,
                                    OPJ_UINT32 stride, OPJ_UINT32 width, OPJ_UINT32 height)
 {
-    OPJ_UINT32 x, y;
+    OPJ_UINT32 x, y, written;
     OPJ_UINT8 *pix;
     const OPJ_UINT8 *beyond;
 
     beyond = pData + stride * height;
     pix = pData;
 
-    x = y = 0U;
+    x = y = written = 0U;
     while (y < height) {
         int c = getc(IN);
         if (c == EOF) {
@@ -561,6 +561,7 @@ static OPJ_BOOL bmp_read_rle8_data(FILE* IN, OPJ_UINT8* pData,
             for (j = 0; (j < c) && (x < width) &&
                     ((OPJ_SIZE_T)pix < (OPJ_SIZE_T)beyond); j++, x++, pix++) {
                 *pix = c1;
+                written++;
             }
         } else {
             c = getc(IN);
@@ -598,6 +599,7 @@ static OPJ_BOOL bmp_read_rle8_data(FILE* IN, OPJ_UINT8* pData,
                     }
                     c1 = (OPJ_UINT8)c1_int;
                     *pix = c1;
+                    written++;
                 }
                 if ((OPJ_UINT32)c & 1U) { /* skip padding byte */
                     c = getc(IN);
@@ -608,6 +610,12 @@ static OPJ_BOOL bmp_read_rle8_data(FILE* IN, OPJ_UINT8* pData,
             }
         }
     }/* while() */
+
+    if (written != width * height) {
+        fprintf(stderr, "warning, image's actual size does not match advertized one\n");
+        return OPJ_FALSE;
+    }
+
     return OPJ_TRUE;
 }