Intravision/reactos
1
0
Fork 0
mirror of https://github.com/reactos/reactos.git synced 2024-07-22 04:08:08 +00:00
Code Issues Packages Projects Releases Wiki Activity

irc : Myrria (from linux xbox project) desc a bug in KiUserExceptionDispatcher and how to fix it.

Browse source 
See issue #2279 for more details.

svn path=/trunk/; revision=26985
This commit is contained in:
Magnus Olsen 2007-06-04 05:50:39 +00:00
parent eb63aa49cc
commit ef546be459
1 changed files with 24 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

24
reactos/dll/ntdll/main/i386/dispatch.S
View file

@ -183,6 +183,30 @@ _KiRaiseUserExceptionDispatcher@0:
.globl _KiUserExceptionDispatcher@8
_KiUserExceptionDispatcher@8:
/* clear the direct flag
* text from bug 2279
* if it not clear it means that if an exception occurs while
* the direction flag is set (typically inside memmove), the
* exception handlers will be called with the direction flag still
* set. The Windows x86-32 and x86-64 ABI requires that the
* direction flag be Calling memset() with a compile-time constant
* size on both GCC and MSVC will result in inlining a "rep stosd"
* instruction. Because of the ABI, they will assume that the
* direction flag is clear and not emit a "cld" instruction.
* Using memset() in an exception handler therefore will
* corrupt memory if the exception occurred during a reverse copy
* such as a forward overlapping memmove().
*
* For reliability and ease of debugging, please add "cld" to the beginning of
* KiUserExceptionDispatcher. Note that the same will be true of x86-64 whenever
* that happens. This does not affect continuing execution; the CONTEXT of the
* exception has the direction flag set and will be restored upon NtContinue.
* KiUserApcDispatcher and KiUserCallbackDispatcher need to be evaluated for this
* issue.
*/
cld
/* Save the Context and Exception Records */
mov ecx, [esp+4]
mov ebx, [esp]