DOCUMENT:Q168006 13-JUN-2001 [sna] TITLE :TN3270 Fails with Access Violation in ntdll!RtlFreeHeap PRODUCT :Microsoft SNA Server PROD/VER:WINDOWS:3.0 OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft SNA Server, version 3.0, on platform(s): - the operating system: Microsoft Windows NT ------------------------------------------------------------------------------- SYMPTOMS ======== The Microsoft SNA Server 3.0 TN3270 Server may fail unexpectedly with an access violation. If DRWTSN32.EXE is configured as the default Windows NT debugger, an entry will be logged in the \DRWTSN32.LOG file as follows: Application exception occurred: App: exe\tn3servr.DBG When: Exception number: c0000005 (access violation) The following are examples of various routines and stack traces which may be indicated when this problem occurs (note that all failures indicate a calling routine of ntdll!RtlFreeHeap): function: RtlpCoalesceFreeBlocks FAULT ->77f7cf1b 8908 mov [eax],ecx *----> Stack Back Trace <----* FramePtr ReturnAd Param#1 Param#2 Param#3 Param#4 Function Name 0c09ff14 77f64c12 01450000 0099a2e8 0c09ff40 00000000 ntdll!RtlpCoalesceFreeBlocks 0c09ff44 10201ba4 01450000 00000000 0099a2f0 762b1da9 ntdll!RtlFreeHeap * or * function: RtlDestroyHeap FAULT ->77f7d0d8 8908 mov [eax],ecx *----> Stack Back Trace <----* FramePtr ReturnAd Param#1 Param#2 Param#3 Param#4 Function Name 0bfaff14 77f64c12 01450000 00a71638 0bfaff40 00000000 ntdll!RtlDestroyHeap 0bfaff44 10201ba4 01450000 00000000 00a71640 762b1da9 ntdll!RtlFreeHeap * or * function: RtlpInsertUnCommittedPages FAULT ->77f642fb 8b4d00 mov ecx,[ebp] *----> Stack Back Trace <----* FramePtr ReturnAd Param#1 Param#2 Param#3 Param#4 Function Name 00e5fcac 77f64ea7 00000000 00ec4000 00066000 00c50000 ntdll!RtlpInsertUnCommittedPages 00e5fcec 77f64c3a 00c50000 00ec3370 0000cf00 001425f8 ntdll!RtlpDeCommitFreeBlock 00e5fd18 0041ad47 00c50000 00000000 00ec3378 0041b22a ntdll!RtlFreeHeap With the NTSD debugger attached, the stack trace may indicate the following failure: NTSD: access violation eax=00000000 ebx=00000000 ecx=0ce83040 edx=01450548 esi=0099fea0 edi=01450000 eip=77f64cfe esp=0c09ff2c ebp=0c09ff44 iopl=0 nv up ei pl zr na po nc cs=001b ss=0023 ds=0023 es=0023 fs=0038 gs=0000 efl=00010246 ntdll!RtlFreeHeap+0x168: 77f64cfe 8908 mov [eax],ecx ds:0023:00000000=???????? 0:013> kb ChildEBP RetAddr Args to Child 0c09ff44 10201ba4 01450000 00000000 0099fec0 ntdll!RtlFreeHeap+0x168 0c09ffec 00000000 0101b2c0 00000000 00000000 Image@10200000!free+0x17 CAUSE ===== This problem was caused after a mismatched version of MSVCRT40.DLL was installed on the Windows NT machine where the TN3270 Server was running. MSVCRT40.DLL supports 'C' runtime library functions which may be used and distributed by third party Windows NT applications developed using Microsoft Visual C++. If a third party application happens to install MSVCRT40.DLL and replace the version installed by Windows NT 4.0 (or SNA Server 3.0), this can lead to TN3270 access violations described above. The following Microsoft VC++ DLL's are shipped by Windows NT 4.0 (and SNA Server 3.0). The "Base" and "File Version" can be viewed using the "DEPENDS" program, or by right-clicking on each DLL using the Windows NT 4.0 "My Computer" program: Module Date Time Size Base File Version MSVCRT.DLL 10/14/96 02:38a 267,536 0x779F0000 4.20.0.6201 MSVCRT40.DLL 10/14/96 02:38a 65,024 0x779D0000 4.2000.0.6172 MFC40.DLL 10/14/96 02:38a 924,432 0x762B0000 4.1.0.6139 MSVCIRT.DLL 10/14/96 02:38a 74,752 0x780A0000 4.20.0.6201 The TN3270 Server access violation was observed when the following MSVCRT40.DLL was installed on the system by a third party application (with the other DLL's matching the versions listed above): Module Date Time Size Base File Version MSVCRT40.DLL 9/16/96 07:50a 312,832 0x10200000 4.0.0.5270 RESOLUTION ========== If an old version of MSVCRT40.DLL is located in the system path, this version should be renamed and the standard version included with Windows NT 4.0 should be reapplied. Here is the process to use to resolve this problem: 1. Run the PATH command to check the current system path. 2. Locate all instances of the above DLL's which exist in the system path (note that the system path may span several drives). 3. Run the DEPENDS program against these DLL's and check their versions against the list documented above (which lists the versions included with Windows NT 4.0) 4. Rename any "old" versions which may exist on the machine, and apply the Windows NT 4.0 versions in their place. If multiple copies of the same DLL exists in the system path, rename all duplicate copies and leave a single instance in the \system32 directory. STATUS ====== Microsoft has confirmed this to be a problem in the Microsoft products that are listed at the beginning of this article. Additional query words: ====================================================================== Keywords : Technology : kbAudDeveloper kbSNAServSearch Version : WINDOWS:3.0 Issue type : kbbug ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2001.