From: Jeffrey Altman <jaltman@your-file-system.com>
Date: Tue, 4 Dec 2012 21:57:36 +0000 (-0500)
Subject: Windows: Prevent lock inversion SetFileRenameInfo
X-Git-Tag: upstream/1.8.0_pre1^2~1733
X-Git-Url: https://git.michaelhowe.org/gitweb/?a=commitdiff_plain;h=b338928bd4663a50963b24d38d337cd1c9f4b87e;p=packages%2Fo%2Fopenafs.git

Windows: Prevent lock inversion SetFileRenameInfo

SetFileRenameInfo calls MmForceSectionClosed() which can call
back to the afs redirector via the Cleanup processing.  AFSCleanup()
requires an exclusive hold of Fcb->Resource so we must obtain the
lock first in AFSSetFileRenameInfo() prior to obtaining the
SectionObjectResource.

Change-Id: If679eeb107f04153a26659971b7f2455eef97c9a
Reviewed-on: http://gerrit.openafs.org/8603
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
---

diff --git a/src/WINNT/afsrdr/kernel/lib/AFSFileInfo.cpp b/src/WINNT/afsrdr/kernel/lib/AFSFileInfo.cpp
index f9ffcdf7c..2a96300fc 100644
--- a/src/WINNT/afsrdr/kernel/lib/AFSFileInfo.cpp
+++ b/src/WINNT/afsrdr/kernel/lib/AFSFileInfo.cpp
@@ -3152,6 +3152,22 @@ AFSSetRenameInfo( IN PIRP Irp)
 
                 pTargetFcb = pTargetDirEntry->ObjectInformation->Fcb;
 
+                //
+                // MmForceSectionClosed() can eventually call back into AFSCleanup
+                // which will need to acquire Fcb->Resource exclusively.  Failure
+                // to obtain it here before holding the SectionObjectResource will
+                // permit the locks to be obtained out of order risking a deadlock.
+                //
+
+                AFSDbgLogMsg( AFS_SUBSYSTEM_LOCK_PROCESSING,
+                              AFS_TRACE_LEVEL_VERBOSE,
+                              "AFSSetRenameInfo Acquiring Fcb lock %08lX EXCL %08lX\n",
+                              &pTargetFcb->NPFcb->Resource,
+                              PsGetCurrentThread());
+
+                AFSAcquireExcl( &pTargetFcb->NPFcb->Resource,
+                                TRUE);
+
                 AFSDbgLogMsg( AFS_SUBSYSTEM_LOCK_PROCESSING,
                               AFS_TRACE_LEVEL_VERBOSE,
                               "AFSSetRenameInfo Acquiring Fcb SectionObject lock %08lX EXCL %08lX\n",
@@ -3182,6 +3198,14 @@ AFSSetRenameInfo( IN PIRP Irp)
                               PsGetCurrentThread());
 
                 AFSReleaseResource( &pTargetFcb->NPFcb->SectionObjectResource);
+
+                AFSDbgLogMsg( AFS_SUBSYSTEM_LOCK_PROCESSING,
+                              AFS_TRACE_LEVEL_VERBOSE,
+                              "AFSSetRenameInfo Releasing Fcb lock %08lX EXCL %08lX\n",
+                              &pTargetFcb->NPFcb->Resource,
+                              PsGetCurrentThread());
+
+                AFSReleaseResource( &pTargetFcb->NPFcb->Resource);
             }
 
             ASSERT( pTargetDirEntry->DirOpenReferenceCount > 0);