OpenLinuxBoot: Fix crash if initrd but no vmlinuz files in autodetect dir

https://github.com/acidanthera/bugtracker/issues/1938

Changelog.md

@@ -11,6 +11,7 @@ OpenCore Changelog
 - Added `flags+=` and `flags-=` arguments to OpenLinuxBoot to simplify setting driver flags if needed
 - Fixed OpenLinuxBoot entry name disambiguation when `LINUX_BOOT_USE_LATEST` flag is clear
 - Updated builtin firmware versions for SMBIOS and the rest
+- Fixed crash in OpenLinuxBoot with partly (re-)installed Linux distro
 
 #### v0.7.7
 - Fixed rare crash caused by register corruption in the entry point

Platform/OpenLinuxBoot/Autodetect.c

@@ -623,18 +623,13 @@ AutodetectBootOptions (
     return EFI_INVALID_PARAMETER;
   }
 
-  //
-  // Standard attached drives on OVMF appear as MBR, so it can be convenient when
-  // debugging to allow entries with incorrect (i.e. specifies no/every drive)
-  // root=... on NOOPT debugging build.
-  //
-//#if !defined(OC_TARGET_NOOPT)
+#if !defined(LINUX_ALLOW_MBR)
   if (CompareGuid (&gPartuuid, &gEfiPartTypeUnusedGuid)) {
     Status = EFI_UNSUPPORTED;
     DEBUG ((DEBUG_WARN, "LNX: Cannot autodetect root on MBR partition - %r\n", Status));
     return Status;
   }
-//#endif
+#endif
 
   //
   // Insert "root=PARTUUID=..." option, followed by "ro" if requested, only if we get to here.
@@ -682,6 +677,8 @@ GenerateEntriesForVmlinuzFiles (
   BOOLEAN                         IsRescue;
 
   ASSERT (DirectoryPath != NULL);
+  ASSERT (mVmlinuzFiles->Count > 0);
+
   DirectoryPathLength = StrLen (DirectoryPath);
 
   for (VmlinuzIndex = 0; VmlinuzIndex < mVmlinuzFiles->Count; VmlinuzIndex++) {
@@ -851,6 +848,13 @@ InternalAutodetectLinux (
   //
   if (!EFI_ERROR (Status)) {
     Status = OcScanDirectory (VmlinuzDirectory, ProcessVmlinuzFile, NULL);
+
+    if (!EFI_ERROR (Status) && mVmlinuzFiles->Count == 0) {
+      //
+      // If initrd files but no vmlinuz files are present in autodetect dir.
+      //
+      Status = EFI_NOT_FOUND;
+    }
   }
 
   if (!EFI_ERROR (Status)) {

Platform/OpenLinuxBoot/LinuxBootInternal.h

@@ -10,6 +10,13 @@
 #define OC_TRACE_GRUB_VARS DEBUG_VERBOSE
 #endif
 
+/*
+  Standard attached drives on OVMF appear as MBR, so it can be convenient when
+  debugging to allow entries with incorrect (i.e. specifies no/every drive)
+  root=... .
+*/
+//#define LINUX_ALLOW_MBR
+
 #include <Uefi.h>
 #include <Library/OcBootManagementLib.h>
 #include <Library/OcMiscLib.h>