Fix a potential memory use-after-free problem following an OOM error.

FossilOrigin-Name: 767ccb1fa11b3e7b895fb8c2e91f79e3b4202907

manifest

@@ -1,5 +1,5 @@
-C Fix\san\sassert()\sso\sthat\sit\stakes\sOOM\serrors\sinto\saccount.
-D 2014-03-04T16:21:18.103
+C Fix\sa\spotential\smemory\suse-after-free\sproblem\sfollowing\san\sOOM\serror.
+D 2014-03-04T18:06:04.531
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 2ef13430cd359f7b361bb863504e227b25cc7f81
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -283,7 +283,7 @@ F src/vdbeInt.h 9ccca0bc7646c918d065943e44bead4bf5de213d
 F src/vdbeapi.c 5bc41aaea448a7fc250902c418f1795859be3820
 F src/vdbeaux.c 0be881d8da9c4413038bb0722de9ecc54788de39
 F src/vdbeblob.c d939997de046b8fcc607cfee4248f3d33dbcca50
-F src/vdbemem.c 10b250f09a3843ee2bcabcadf50ca21fc3ff1f87
+F src/vdbemem.c 1b1ca620f2638e800a5bef6508d1c4320a3a4f11
 F src/vdbesort.c 46801acb342e5e4c07ba1777fe58880c143abb59
 F src/vdbetrace.c 6f52bc0c51e144b7efdcfb2a8f771167a8816767
 F src/vtab.c 21b932841e51ebd7d075e2d0ad1415dce8d2d5fd
@@ -1155,7 +1155,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
 F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
-P 2879234b7c373be422af3fe180cae9840943e29a
-R 2b2904237b1b4d9d5fce461560fa87d0
+P 53f6ec792f5f62fcdbf25e0fce5545dd1c3048a4
+R b289979daf151f0fbafb28fbb7956db7
 U drh
-Z 60f0b04eed352e57b9c570cb2f1addac
+Z f463125a8b67b6cdc900f4915889d477

manifest.uuid

@@ -1 +1 @@
-53f6ec792f5f62fcdbf25e0fce5545dd1c3048a4
+767ccb1fa11b3e7b895fb8c2e91f79e3b4202907

src/vdbemem.c

@@ -122,6 +122,7 @@ int sqlite3VdbeMemGrow(Mem *pMem, int n, int bPreserve){
     }
     if( pMem->zMalloc==0 ){
       VdbeMemRelease(pMem);
+      pMem->z = 0;
       pMem->flags = MEM_Null;  
       return SQLITE_NOMEM;
     }