[reactos] 03/05: [FASTFAT] Avoid a use after free in VfatCloseFile.

[Thomas Faber]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=bc002f17087d912f1148b9...

commit bc002f17087d912f1148b988299aa523f28e927c
Author:     Thomas Faber [e-mail]
AuthorDate: Sat Jan 12 16:25:52 2019 +0100
Commit:     Thomas Faber [e-mail]
CommitDate: Sat Jan 12 16:27:37 2019 +0100

[FASTFAT] Avoid a use after free in VfatCloseFile.
---
 drivers/filesystems/fastfat/close.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/filesystems/fastfat/close.c b/drivers/filesystems/fastfat/close.c
index b6c250f92c..57efdad97a 100644
--- a/drivers/filesystems/fastfat/close.c
+++ b/drivers/filesystems/fastfat/close.c
@@ -163,6 +163,7 @@ VfatCloseFile(
 {
     PVFATFCB pFcb;
     PVFATCCB pCcb;
+    BOOLEAN IsVolume;
     NTSTATUS Status = STATUS_SUCCESS;

DPRINT("VfatCloseFile(DeviceExt %p, FileObject %p)\n",
@@ -177,6 +178,8 @@ VfatCloseFile(
         return STATUS_SUCCESS;
     }

+    IsVolume = BooleanFlagOn(pFcb->Flags, FCB_IS_VOLUME);
+
     if (pCcb)
     {
         vfatDestroyCCB(pCcb);
@@ -194,7 +197,7 @@ VfatCloseFile(
     FileObject->SectionObjectPointer = NULL;

#ifdef ENABLE_SWAPOUT
-    if (BooleanFlagOn(pFcb->Flags, FCB_IS_VOLUME) && DeviceExt->OpenHandleCount == 0)
+    if (IsVolume && DeviceExt->OpenHandleCount == 0)
     {
         VfatCheckForDismount(DeviceExt, FALSE);
     }