Changeset 93113 in vbox for trunk/src

Timestamp:

Dec 31, 2021 11:42:50 PM (3 years ago)

Author:

vboxsync

Message:

IPRt/fatvfs.cpp: Fixed off by two cluster validation bug causing trouble accessing files using one of the last two clusters on a disk.

File:

• trunk/src/VBox/Runtime/common/fs/fatvfs.cpp (modified) (4 diffs)

trunk/src/VBox/Runtime/common/fs/fatvfs.cpp

@@ -1216 +1216 @@
     {
         /* Validate the cluster, checking for end of file. */
-        if (   idxCluster >= pFatCache->cClusters
-            || idxCluster <  FAT_FIRST_DATA_CLUSTER)
+        if ((uint32_t)(idxCluster - FAT_FIRST_DATA_CLUSTER) >= pFatCache->cClusters)
         {
             if (idxCluster >= FAT_FIRST_FAT12_EOC)
                 return VINF_SUCCESS;
+            Log(("Fat/ReadChain12: bogus cluster %#x vs %#x total\n", idxCluster, pFatCache->cClusters));
             return VERR_VFS_BOGUS_OFFSET;
         }
@@ -1265 +1265 @@
     {
         /* Validate the cluster, checking for end of file. */
-        if (   idxCluster >= pFatCache->cClusters
-            || idxCluster <  FAT_FIRST_DATA_CLUSTER)
+        if ((uint32_t)(idxCluster - FAT_FIRST_DATA_CLUSTER) >= pFatCache->cClusters)
         {
             if (idxCluster >= FAT_FIRST_FAT16_EOC)
                 return VINF_SUCCESS;
+            Log(("Fat/ReadChain16: bogus cluster %#x vs %#x total\n", idxCluster, pFatCache->cClusters));
             return VERR_VFS_BOGUS_OFFSET;
         }
@@ -1297 +1297 @@
     {
         /* Validate the cluster, checking for end of file. */
-        if (   idxCluster >= pFatCache->cClusters
-            || idxCluster <  FAT_FIRST_DATA_CLUSTER)
+        if ((uint32_t)(idxCluster - FAT_FIRST_DATA_CLUSTER) >= pFatCache->cClusters)
         {
             if (idxCluster >= FAT_FIRST_FAT32_EOC)
                 return VINF_SUCCESS;
+            Log(("Fat/ReadChain32: bogus cluster %#x vs %#x total\n", idxCluster, pFatCache->cClusters));
             return VERR_VFS_BOGUS_OFFSET;
         }
@@ -2598 +2598 @@
 
 /**
- * Instantiates a new directory.
+ * Instantiates a new file.
  *
  * @returns IPRT status code.