[pschweitzer] 72186: [NTOSKRNL] While attempting to read data from disk in CcReadVirtualAddress(), always align our read size by pages. That means that even on boundaries, we will read a complete p...

Author: pschweitzer
Date: Wed Aug 10 11:52:30 2016
New Revision: 72186

URL: http://svn.reactos.org/svn/reactos?rev=72186&view=rev
Log:
[NTOSKRNL]
While attempting to read data from disk in CcReadVirtualAddress(), always align our read
size by pages.
That means that even on boundaries, we will read a complete page.
This fixes FSD relying on Cc to properly align reads and thus poorly failing in disk.sys
because of unaligned reads.
Notably, it helps MS FastFAT loading a bit farther in ReactOS (but it still fails :-().
This also fixes a few kmtests.

CORE-11003
CORE-11819

Modified:
    trunk/reactos/ntoskrnl/cc/copy.c

Modified: trunk/reactos/ntoskrnl/cc/copy.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/cc/copy.c?rev=721…
==============================================================================
--- trunk/reactos/ntoskrnl/cc/copy.c	[iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/cc/copy.c	[iso-8859-1] Wed Aug 10 11:52:30 2016
@@ -65,7 +65,7 @@
 CcReadVirtualAddress (
     PROS_VACB Vacb)
 {
-    ULONG Size;
+    ULONG Size, Pages;
     PMDL Mdl;
     NTSTATUS Status;
     IO_STATUS_BLOCK IoStatus;
@@ -77,7 +77,10 @@
         Size = VACB_MAPPING_GRANULARITY;
     }
 
-    Mdl = IoAllocateMdl(Vacb->BaseAddress, Size, FALSE, FALSE, NULL);
+    Pages = BYTES_TO_PAGES(Size);
+    ASSERT(Pages * PAGE_SIZE <= VACB_MAPPING_GRANULARITY);
+
+    Mdl = IoAllocateMdl(Vacb->BaseAddress, Pages * PAGE_SIZE, FALSE, FALSE, NULL);
     if (!Mdl)
     {
         return STATUS_INSUFFICIENT_RESOURCES;