[PATCH v2] ntoskrnl.exe: fix handling relocations on page boundary

[Rafał H]

Code is only used for non-page-aligned device drivers.
Previously if relocation was happening on page boundary it crashed
because only one page had changed protection in load_driver_module.
Now code is copied from ntdll and changes protection for all module pages
before actual relocation starts.
Fixes running MTA: San Andreas game.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=28254
Signed-off-by: Rafał Harabień <rafalh92 at outlook.com>
---
 dlls/ntoskrnl.exe/ntoskrnl.c | 102 +++++++++++++++++++++++++++--------
 1 file changed, 80 insertions(+), 22 deletions(-)

diff --git a/dlls/ntoskrnl.exe/ntoskrnl.c b/dlls/ntoskrnl.exe/ntoskrnl.c
index d8a87a6ad0..e130fac302 100644
--- a/dlls/ntoskrnl.exe/ntoskrnl.c
+++ b/dlls/ntoskrnl.exe/ntoskrnl.c
@@ -25,6 +25,7 @@
 #include "wine/port.h"
 
 #include <stdarg.h>
+#include <assert.h>
 
 #define NONAMELESSUNION
 #define NONAMELESSSTRUCT
@@ -3295,6 +3296,84 @@ static LDR_MODULE *find_ldr_module( HMODULE module )
     return ldr;
 }
 
+/* convert PE image VirtualAddress to Real Address */
+static inline void *get_rva( HMODULE module, DWORD va )
+{
+    return (void *)((char *)module + va);
+}
+
+/* Copied from ntdll with checks for page alignment and characteristics removed */
+static NTSTATUS perform_relocations( void *module, SIZE_T len )
+{
+    IMAGE_NT_HEADERS *nt;
+    char *base;
+    IMAGE_BASE_RELOCATION *rel, *end;
+    const IMAGE_DATA_DIRECTORY *relocs;
+    const IMAGE_SECTION_HEADER *sec;
+    INT_PTR delta;
+    ULONG protect_old[96], i;
+
+    nt = RtlImageNtHeader( module );
+    base = (char *)nt->OptionalHeader.ImageBase;
+
+    assert( module != base );
+
+    relocs = &nt->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC];
+
+    if (nt->FileHeader.Characteristics & IMAGE_FILE_RELOCS_STRIPPED)
+    {
+        WARN( "Need to relocate module from %p to %p, but there are no relocation records\n",
+              base, module );
+        return STATUS_CONFLICTING_ADDRESSES;
+    }
+
+    if (!relocs->Size) return STATUS_SUCCESS;
+    if (!relocs->VirtualAddress) return STATUS_CONFLICTING_ADDRESSES;
+
+    if (nt->FileHeader.NumberOfSections > ARRAY_SIZE( protect_old ))
+        return STATUS_INVALID_IMAGE_FORMAT;
+
+    sec = (const IMAGE_SECTION_HEADER *)((const char *)&nt->OptionalHeader +
+                                         nt->FileHeader.SizeOfOptionalHeader);
+    for (i = 0; i < nt->FileHeader.NumberOfSections; i++)
+    {
+        void *addr = get_rva( module, sec[i].VirtualAddress );
+        SIZE_T size = sec[i].SizeOfRawData;
+        NtProtectVirtualMemory( NtCurrentProcess(), &addr,
+                                &size, PAGE_READWRITE, &protect_old[i] );
+    }
+
+    TRACE( "relocating from %p-%p to %p-%p\n",
+           base, base + len, module, (char *)module + len );
+
+    rel = get_rva( module, relocs->VirtualAddress );
+    end = get_rva( module, relocs->VirtualAddress + relocs->Size );
+    delta = (char *)module - base;
+
+    while (rel < end - 1 && rel->SizeOfBlock)
+    {
+        if (rel->VirtualAddress >= len)
+        {
+            WARN( "invalid address %p in relocation %p\n", get_rva( module, rel->VirtualAddress ), rel );
+            return STATUS_ACCESS_VIOLATION;
+        }
+        rel = LdrProcessRelocationBlock( get_rva( module, rel->VirtualAddress ),
+                                         (rel->SizeOfBlock - sizeof(*rel)) / sizeof(USHORT),
+                                         (USHORT *)(rel + 1), delta );
+        if (!rel) return STATUS_INVALID_IMAGE_FORMAT;
+    }
+
+    for (i = 0; i < nt->FileHeader.NumberOfSections; i++)
+    {
+        void *addr = get_rva( module, sec[i].VirtualAddress );
+        SIZE_T size = sec[i].SizeOfRawData;
+        NtProtectVirtualMemory( NtCurrentProcess(), &addr,
+                                &size, protect_old[i], &protect_old[i] );
+    }
+
+    return STATUS_SUCCESS;
+}
+
 /* load the driver module file */
 static HMODULE load_driver_module( const WCHAR *name )
 {
@@ -3318,28 +3397,7 @@ static HMODULE load_driver_module( const WCHAR *name )
     if (nt->OptionalHeader.SectionAlignment < info.PageSize ||
         !(nt->FileHeader.Characteristics & IMAGE_FILE_DLL))
     {
-        DWORD old;
-        IMAGE_BASE_RELOCATION *rel, *end;
-
-        if ((rel = RtlImageDirectoryEntryToData( module, TRUE, IMAGE_DIRECTORY_ENTRY_BASERELOC, &size )))
-        {
-            TRACE( "%s: relocating from %p to %p\n", wine_dbgstr_w(name), (char *)module - delta, module );
-            end = (IMAGE_BASE_RELOCATION *)((char *)rel + size);
-            while (rel < end && rel->SizeOfBlock)
-            {
-                void *page = (char *)module + rel->VirtualAddress;
-                VirtualProtect( page, info.PageSize, PAGE_EXECUTE_READWRITE, &old );
-                rel = LdrProcessRelocationBlock( page, (rel->SizeOfBlock - sizeof(*rel)) / sizeof(USHORT),
-                                                 (USHORT *)(rel + 1), delta );
-                if (old != PAGE_EXECUTE_READWRITE) VirtualProtect( page, info.PageSize, old, &old );
-                if (!rel) goto error;
-            }
-            /* make sure we don't try again */
-            size = FIELD_OFFSET( IMAGE_NT_HEADERS, OptionalHeader ) + nt->FileHeader.SizeOfOptionalHeader;
-            VirtualProtect( nt, size, PAGE_READWRITE, &old );
-            nt->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC].VirtualAddress = 0;
-            VirtualProtect( nt, size, old, &old );
-        }
+        perform_relocations(module, nt->OptionalHeader.SizeOfImage);
     }
 
     /* make sure imports are relocated too */
-- 
2.17.1