Some cleanup

Cisco-Talos · Aug 8, 2024 · 6c03975 · 6c03975
1 parent 2bd003b
commit 6c03975
Showing 1 changed file with 37 additions and 1 deletion.
diff --git a/libclamav/ole2_extract_images.h b/libclamav/ole2_extract_images.h
@@ -397,7 +397,7 @@ typedef struct {
 } ole2_image_directory_t;
 
 /*
- * This structure is used to keep track of a poiner's offset, to determine if it will cross
+ * This structure is used to keep track of a pointer's offset, to determine if it will cross
  * a block that is used by the DIFAT
  * https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-cfb/05060311-bfce-4b12-874d-71fd4ce63aea
  * The strategy is to keep updating ptr to point to the data structure that is currently being read,
@@ -427,6 +427,10 @@ typedef struct __attribute__((packed)) {
 
 } ole2_pointer_t;
 
+static void update_pointer(ole2_pointer_t * ptr, size_t offset) {
+    ptr->ptr = &(ptr->ptr[offset]);
+}
+
 /* https://learn.microsoft.com/en-us/openspecs/office_file_formats/ms-odraw/5dc1b9ed-818c-436f-8a4f-905a7ebb1ba9 */
 typedef struct __attribute__((packed)) {
     uint16_t recVer_recInstance;
@@ -690,7 +694,11 @@ static void saveImageFile( cli_ctx * ctx, ole2_header_t * ole2Hdr, ole2_pointer_
                     /*Get more space from the fmap to account for the extra block*/
                     const uint8_t * ptr = fmap_need_off_once(ole2Hdr->map, ole2Ptr->stream_file_offset, (ole2Ptr->ptr - ole2Ptr->base_ptr) + increment + size);
                     if (ptr != ole2Ptr->base_ptr) {
+#if 0
                         ole2Ptr->ptr = &(ptr[ole2Ptr->ptr - ole2Ptr->base_ptr]);
+#else
+                        update_pointer(ole2Ptr, ole2Ptr->ptr - ole2Ptr->base_ptr);
+#endif
                         ole2Ptr->base_ptr = ptr;
                     }
                 }
@@ -729,7 +737,11 @@ static void saveImageFile( cli_ctx * ctx, ole2_header_t * ole2Hdr, ole2_pointer_
     }
 
 done:
+#if 0
     ole2Ptr->ptr = &(ole2Ptr->ptr[size + totalIncrement]);
+#else
+    update_pointer(ole2Ptr, size + totalIncrement);
+#endif
 
     if (tempfile && !ctx->engine->keeptmp) {
         remove(tempfile);
@@ -762,7 +774,11 @@ static void processOfficeArtBlipGeneric(cli_ctx * ctx, ole2_header_t * ole2Hdr,
     }
     offset += bytesAfterUIDs; /*metafile header*/
 
+#if 0
     ole2Ptr->ptr = &(ole2Ptr->ptr[offset]);
+#else
+    update_pointer(ole2Ptr, offset);
+#endif
     saveImageFile(ctx, ole2Hdr, ole2Ptr, rh->recLen - offset);
 }
 
@@ -794,7 +810,11 @@ static void processOfficeArtBlipJPEG(cli_ctx * ctx, ole2_header_t * ole2Hdr, Off
     }
     offset += 1; /*metafile header*/
 
+#if 0
     ole2Ptr->ptr = &(ole2Ptr->ptr[offset]);
+#else
+    update_pointer(ole2Ptr, offset);
+#endif
     saveImageFile(ctx, ole2Hdr, ole2Ptr, rh->recLen - offset);
 }
 
@@ -834,7 +854,11 @@ static size_t processOfficeArtBlip(cli_ctx * ctx, ole2_header_t * ole2Hdr, ole2_
 #define RECTYPE_OFFICE_ART_BLIP_TIFF 0xf029
 #define RECTYPE_OFFICE_ART_BLIP_JPEG2 0xf02a
 
+#if 0
     ole2Ptr->ptr = &(ole2Ptr->ptr[offset]);
+#else
+    update_pointer(ole2Ptr, offset);
+#endif
     switch (rh.recType) {
         case RECTYPE_OFFICE_ART_BLIP_EMF:
             processOfficeArtBlipEMF(ctx, ole2Hdr, &rh, ole2Ptr);
@@ -865,7 +889,11 @@ static size_t processOfficeArtBlip(cli_ctx * ctx, ole2_header_t * ole2Hdr, ole2_
     }
 
 done:
+#if 0
     ole2Ptr->ptr = &(ole2Ptr->ptr[sizeof(rh) + rh.recLen]);
+#else
+    update_pointer(ole2Ptr, sizeof(rh) + rh.recLen);
+#endif
     return (sizeof(rh) + rh.recLen);
 }
 
@@ -892,11 +920,19 @@ static size_t processOfficeArtFBSE(cli_ctx * ctx, ole2_header_t *hdr, OfficeArtR
 
     offset += fbse.cbName;
 
+#if 0
     ole2Ptr->ptr = &(ole2Ptr->ptr[offset]);
+#else
+    update_pointer(ole2Ptr, offset);
+#endif
     if (imageHeader->recLen == (sizeof(OfficeArtFBSEKnown) + fbse.cbName + fbse.size)) {
         /* The BLIP is embedded in this record*/ 
         processOfficeArtBlip(ctx, hdr, ole2Ptr);
+#if 0
         ole2Ptr->ptr = &(ole2Ptr->ptr[fbse.size]);
+#else
+    update_pointer(ole2Ptr, fbse.size);
+#endif
         offset += fbse.size;
     } else {
         /* The BLIP is in the 'WordDocument' stream. */