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List:       kde-announce
Subject:    Re: Security patch for KDE libraries
From:       Matthias Hoelzer-Kluepfel <mhk () caldera ! de>
Date:       1999-03-03 9:17:42
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Hi,

due to some internal communication problems, that patch I
announced yesterday did not yet arrive on ftp.kde.org. As the
actual patch is much shorter than the annoncement, I have
attached it to this mail.

Sorry for this inconvenience.

Bye,
Matthias.

================================================================
 Matthias Hoelzer-Kluepfel		        hoelzer@kde.org
						 mhk@caldera.de
----------------------------------------------------------------

["kdelibs-1.1-connect.patch" (APPLICATION/X-PATCH)]

--- kdelibs-1.1/mediatool/connect.c.connect	Wed Dec  9 11:51:17 1998
+++ kdelibs-1.1/mediatool/connect.c	Tue Feb 23 11:01:42 1999
@@ -24,6 +24,8 @@
 #include <sys/ipc.h>
 #include <sys/shm.h>
 #include <sys/types.h>
+#include <fcntl.h>
+#include <errno.h>
 #include "mediatool.h"
 #include "chunk.h"
 
@@ -171,9 +173,7 @@
 void MdConnectNew(MediaCon *mcon)
 {
   char	        *tmpadr, *StartAdr;
-  struct stat	finfo;
   int		ret, ref, newRefnum;
-  FILE		*fid;
   MdCh_IHDR	HeadChunk;
   MdCh_KEYS	KeysChunk;
   MdCh_STAT	StatChunk;
@@ -194,15 +194,26 @@
   strcpy(pathkey,mckey);
   sprintf(pathkey+strlen(pathkey), "%i", newRefnum);
 
-  ret = stat(pathkey, &finfo);
-  if ( ret < 0 ) {
-    fid = fopen(pathkey, "w");
-    if ( fid==NULL ) {
+  /* Try to open temp file safely. We can't just do a
+   *	if (stat() < 0)
+   *		fopen(path, "w")
+   * because that is still raceable by flipping symlinks.
+   *
+   * ftok() is a stupid kludge anyway, and is likely to clutter
+   * your disk with stupid temp files. A better approach may be
+   * to do a SHM_INFO (get max shmid), loop over all shmids and
+   * do a SHM_STAT to see whether we can attach to that segment,
+   * if yes, attach to it and check for MDTO signature and
+   * pathkey in HeadChunk.ipcfname.	--okir
+   */
+  ret = open(pathkey, O_WRONLY|O_CREAT|O_EXCL, 0600);
+  if (ret >= 0)
+      close(ret);
+  else if (errno != EEXIST)
+    {
       LogError("Could not create a shared talk key file.");
       return;
     }
-    fclose(fid);
-  }
 
   /* Now it is guaranteed, a file exists. Get the adress. */
   /* Get the talk key for that file. */


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