[FREELDR] fs.c: Minor refactoring in ArcOpen(); fix a memory leak (re…

…actos#7385)

- `ArcOpen()`: flatten the registered-device search for-loop.
  Limit it to just the device search, and exit early.
  The rest of the initialization is now done outside the loop.

- The `DeviceName` string pointer may have been allocated from
  the heap, for path normalization (see `NormalizeArcDeviceName()`).
  This pointer is then only used in the device search loop and not
  nused anymore afterwards. The old code didn't free this pointer
  and memory could leak. This is now fixed easily, thanks to the
  loop flattening.

- Rename `DEVICE` member `Prefix` to `DeviceName`; SAL-annotate
  `FsRegisterDevice()`.

boot/freeldr/freeldr/include/fs.h

@@ -52,7 +52,11 @@ FsOpenFile(
 ULONG FsGetNumPathParts(PCSTR Path);
 VOID  FsGetFirstNameFromPath(PCHAR Buffer, PCSTR Path);
 
-VOID FsRegisterDevice(CHAR* Prefix, const DEVVTBL* FuncTable);
+VOID
+FsRegisterDevice(
+    _In_ PCSTR DeviceName,
+    _In_ const DEVVTBL* FuncTable);
+
 PCWSTR FsGetServiceName(ULONG FileId);
 VOID  FsSetDeviceSpecific(ULONG FileId, VOID* Specific);
 VOID* FsGetDeviceSpecific(ULONG FileId);

boot/freeldr/freeldr/lib/fs/fs.c

@@ -43,7 +43,7 @@ typedef struct tagDEVICE
 {
     LIST_ENTRY ListEntry;
     const DEVVTBL* FuncTable;
-    CHAR* Prefix;
+    PSTR DeviceName;
     ULONG DeviceId;
     ULONG ReferenceCount;
 } DEVICE;
@@ -167,78 +167,81 @@ ARC_STATUS ArcOpen(CHAR* Path, OPENMODE OpenMode, ULONG* FileId)
     if (!DeviceName)
         return ENOMEM;
 
-    /* Search for the device */
     if (OpenMode == OpenReadOnly || OpenMode == OpenWriteOnly)
         DeviceOpenMode = OpenMode;
     else
         DeviceOpenMode = OpenReadWrite;
 
-    pEntry = DeviceListHead.Flink;
-    while (pEntry != &DeviceListHead)
+    /* Search for the registered device */
+    pDevice = NULL;
+    for (pEntry = DeviceListHead.Flink;
+         pEntry != &DeviceListHead;
+         pEntry = pEntry->Flink)
     {
         pDevice = CONTAINING_RECORD(pEntry, DEVICE, ListEntry);
-        if (strncmp(pDevice->Prefix, DeviceName, Length) == 0)
-        {
-            /* OK, device found. Is it already opened? */
-            if (pDevice->ReferenceCount == 0)
-            {
-                /* Find some room for the device */
-                for (DeviceId = 0; ; ++DeviceId)
-                {
-                    if (DeviceId >= _countof(FileData))
-                        return EMFILE;
-                    if (!FileData[DeviceId].FuncTable)
-                        break;
-                }
-
-                /* Try to open the device */
-                FileData[DeviceId].FuncTable = pDevice->FuncTable;
-                Status = pDevice->FuncTable->Open(pDevice->Prefix, DeviceOpenMode, &DeviceId);
-                if (Status != ESUCCESS)
-                {
-                    FileData[DeviceId].FuncTable = NULL;
-                    return Status;
-                }
-                else if (!*FileName)
-                {
-                    /* Done, caller wanted to open the raw device */
-                    *FileId = DeviceId;
-                    pDevice->ReferenceCount++;
-                    return ESUCCESS;
-                }
-
-                /* Try to detect the file system */
-                {
-                    ULONG fs;
-                    for (fs = 0; fs < _countof(FileSystems); ++fs)
-                    {
-                        FileData[DeviceId].FileFuncTable = FileSystems[fs](DeviceId);
-                        if (FileData[DeviceId].FileFuncTable)
-                            break;
-                    }
-                }
-                if (!FileData[DeviceId].FileFuncTable)
-                {
-                    /* Error, unable to detect the file system */
-                    pDevice->FuncTable->Close(DeviceId);
-                    FileData[DeviceId].FuncTable = NULL;
-                    return ENODEV;
-                }
-
-                pDevice->DeviceId = DeviceId;
-            }
-            else
-            {
-                DeviceId = pDevice->DeviceId;
-            }
-            pDevice->ReferenceCount++;
+        if (strncmp(pDevice->DeviceName, DeviceName, Length) == 0)
             break;
-        }
-        pEntry = pEntry->Flink;
     }
+
+    /* Cleanup */
+    if (DeviceName != Path)
+        FrLdrTempFree(DeviceName, TAG_DEVICE_NAME);
+    DeviceName = NULL;
+
     if (pEntry == &DeviceListHead)
         return ENODEV;
 
+    /* OK, device found. Is it already opened? */
+    if (pDevice->ReferenceCount == 0)
+    {
+        /* Find some room for the device */
+        for (DeviceId = 0; ; ++DeviceId)
+        {
+            if (DeviceId >= _countof(FileData))
+                return EMFILE;
+            if (!FileData[DeviceId].FuncTable)
+                break;
+        }
+
+        /* Try to open the device */
+        FileData[DeviceId].FuncTable = pDevice->FuncTable;
+        Status = pDevice->FuncTable->Open(pDevice->DeviceName, DeviceOpenMode, &DeviceId);
+        if (Status != ESUCCESS)
+        {
+            FileData[DeviceId].FuncTable = NULL;
+            return Status;
+        }
+        else if (!*FileName)
+        {
+            /* Done, caller wanted to open the raw device */
+            *FileId = DeviceId;
+            pDevice->ReferenceCount++;
+            return ESUCCESS;
+        }
+
+        /* Try to detect the file system */
+        for (ULONG fs = 0; fs < _countof(FileSystems); ++fs)
+        {
+            FileData[DeviceId].FileFuncTable = FileSystems[fs](DeviceId);
+            if (FileData[DeviceId].FileFuncTable)
+                break;
+        }
+        if (!FileData[DeviceId].FileFuncTable)
+        {
+            /* Error, unable to detect the file system */
+            pDevice->FuncTable->Close(DeviceId);
+            FileData[DeviceId].FuncTable = NULL;
+            return ENODEV;
+        }
+
+        pDevice->DeviceId = DeviceId;
+    }
+    else
+    {
+        DeviceId = pDevice->DeviceId;
+    }
+    pDevice->ReferenceCount++;
+
     /* At this point, device is found and opened. Its file id is stored
      * in DeviceId, and FileData[DeviceId].FileFuncTable contains what
      * needs to be called to open the file */
@@ -435,22 +438,25 @@ VOID FsGetFirstNameFromPath(PCHAR Buffer, PCSTR Path)
     TRACE("FsGetFirstNameFromPath() Path = %s FirstName = %s\n", Path, Buffer);
 }
 
-VOID FsRegisterDevice(CHAR* Prefix, const DEVVTBL* FuncTable)
+VOID
+FsRegisterDevice(
+    _In_ PCSTR DeviceName,
+    _In_ const DEVVTBL* FuncTable)
 {
     DEVICE* pNewEntry;
     SIZE_T Length;
 
-    TRACE("FsRegisterDevice() Prefix = %s\n", Prefix);
+    TRACE("FsRegisterDevice(%s)\n", DeviceName);
 
-    Length = strlen(Prefix) + 1;
+    Length = strlen(DeviceName) + 1;
     pNewEntry = FrLdrTempAlloc(sizeof(DEVICE) + Length, TAG_DEVICE);
     if (!pNewEntry)
         return;
     pNewEntry->FuncTable = FuncTable;
     pNewEntry->DeviceId = INVALID_FILE_ID;
     pNewEntry->ReferenceCount = 0;
-    pNewEntry->Prefix = (CHAR*)(pNewEntry + 1);
-    RtlCopyMemory(pNewEntry->Prefix, Prefix, Length);
+    pNewEntry->DeviceName = (PSTR)(pNewEntry + 1);
+    RtlCopyMemory(pNewEntry->DeviceName, DeviceName, Length);
 
     InsertHeadList(&DeviceListHead, &pNewEntry->ListEntry);
 }