Detect databases whose schema is corrupted using a CREATE TABLE AS statement and issue an appropriate error message.

Check-in [d75e6765], https://www.sqlite.org/src/info/d75e67654aa9620b

https://bugs.launchpad.net/ubuntu/+source/sqlite3/+bug/1756349

https://nvd.nist.gov/vuln/detail/CVE-2018-8740

--- sqlite3.c.orig	2018-03-22 07:08:21 UTC

+++ sqlite3.c

@@ -103474,8 +103474,6 @@ SQLITE_PRIVATE void sqlite3EndTable(

   p = pParse->pNewTable;

   if( p==0 ) return;

-  assert( !db->init.busy || !pSelect );

-

   /* If the db->init.busy is 1 it means we are reading the SQL off the

   ** "sqlite_master" or "sqlite_temp_master" table on the disk.

   ** So do not write to the disk again.  Extract the root page number

@@ -103486,6 +103484,10 @@ SQLITE_PRIVATE void sqlite3EndTable(

   ** table itself.  So mark it read-only.

   */

   if( db->init.busy ){

+    if( pSelect ){

+      sqlite3ErrorMsg(pParse, "");

+      return;

+    }

     p->tnum = db->init.newTnum;

     if( p->tnum==1 ) p->tabFlags |= TF_Readonly;

   }

@@ -117813,7 +117815,7 @@ static void corruptSchema(

     char *z;

     if( zObj==0 ) zObj = "?";

     z = sqlite3MPrintf(db, "malformed database schema (%s)", zObj);

-    if( zExtra ) z = sqlite3MPrintf(db, "%z - %s", z, zExtra);

+    if( zExtra && zExtra[0] ) z = sqlite3MPrintf(db, "%z - %s", z, zExtra);

     sqlite3DbFree(db, *pData->pzErrMsg);

     *pData->pzErrMsg = z;

   }

PORTREVISION=	1