02/02: [NTOS:CC] Don't read past the end of the file in CcPerformReadAhead.

[Thomas Faber]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=a2f77ee3fb74553744f95…

commit a2f77ee3fb74553744f95d5ef0963cadda97302f
Author:     Thomas Faber <thomas.faber(a)reactos.org>
AuthorDate: Tue Feb 20 13:49:54 2018 +0100
Commit:     Thomas Faber <thomas.faber(a)reactos.org>
CommitDate: Thu Feb 22 14:03:05 2018 +0100

    [NTOS:CC] Don't read past the end of the file in CcPerformReadAhead.
---
 ntoskrnl/cc/copy.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/ntoskrnl/cc/copy.c b/ntoskrnl/cc/copy.c
index 43287774a3..496cef6d4d 100644
--- a/ntoskrnl/cc/copy.c
+++ b/ntoskrnl/cc/copy.c
@@ -517,6 +517,16 @@ CcPerformReadAhead(
     /* Remember it's locked */
     Locked = TRUE;
 
+    /* Don't read past the end of the file */
+    if (CurrentOffset >= SharedCacheMap->FileSize.QuadPart)
+    {
+        goto Clear;
+    }
+    if (CurrentOffset + Length > SharedCacheMap->FileSize.QuadPart)
+    {
+        Length = SharedCacheMap->FileSize.QuadPart - CurrentOffset;
+    }
+
     /* Next of the algorithm will lock like CcCopyData with the slight
      * difference that we don't copy data back to an user-backed buffer
      * We just bring data into Cc