Make the sqlite_rename_column() SQL function resistant to problems caused

by OOMs and/or malformed parameters submitted by hostile application code.
Also add additional comments to the RENAME COLUMN logic.

FossilOrigin-Name: 87743ddef11749b4017d60abc297abfd673e02a26a2ae45ffec861327578aa30

diff --git a/manifest b/manifest
index d6c9346159d74185e949759aa8e10d7b59ba6045..11e97f88c9c2556fc811d3b06cfceef6c0ebf134 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\slegacy\scomments\son\sToken.\s\sBegin\scommenting\sthe\snew\sALTER\sTABLE\sRENAME\nCOLUMN\scode.\s\sFix\sa\smemory\sleak\sin\sthe\ssqlite_rename_column()\sSQL\sfunction.
-D 2018-08-13T15:09:48.567
+C Make\sthe\ssqlite_rename_column()\sSQL\sfunction\sresistant\sto\sproblems\scaused\nby\sOOMs\sand/or\smalformed\sparameters\ssubmitted\sby\shostile\sapplication\scode.\nAlso\sadd\sadditional\scomments\sto\sthe\sRENAME\sCOLUMN\slogic.
+D 2018-08-13T17:02:26.434
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 0a3a6c81e6fcb969ff9106e882f0a08547014ba463cb6beca4c4efaecc924ee6
@@ -432,7 +432,7 @@ F spec.template 86a4a43b99ebb3e75e6b9a735d5fd293a24e90ca
 F sqlite.pc.in 42b7bf0d02e08b9e77734a47798d1a55a9e0716b
 F sqlite3.1 fc7ad8990fc8409983309bb80de8c811a7506786
 F sqlite3.pc.in 48fed132e7cb71ab676105d2a4dc77127d8c1f3a
-F src/alter.c 7a8e8f14b07063973b772b07921bcc54db36e26e8aae14d2584446ed5af9e513
+F src/alter.c 5367a5483812b08662f17e7eb5e1891cc0996f9b6e297955ce03454c508d3c79
 F src/analyze.c 3dc6b98cf007b005af89df165c966baaa48e8124f38c87b4d2b276fe7f0b9eb9
 F src/attach.c 4bd5b92633671d3e8ce431153ebb1893b50335818423b5373f3f27969f79769a
 F src/auth.c 32a5bbe3b755169ab6c66311c5225a3cd4f75a46c041f7fb117e0cbb68055114
@@ -1756,7 +1756,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 0b28dd5c2e4908d5e49eaedd359492e46de8af3bf84120f4683b3ea906882fbf
-R 8e4aad63439996e323e3c103c6b55b1d
+P 32edc8920376aabb84ebe1900eaa9512d23f1b44d6459e4916dc6b07db66e27c
+R dded0a1ea7b07b29f53ec6b813829626
 U drh
-Z 82791a60e4da34a95b2d48254121d988
+Z 21a9b725df605fe8e7c9a80550758727

diff --git a/manifest.uuid b/manifest.uuid
index aa113d45ed837ccd4db954660aaf7d6a0e4b5d47..3b2e0343e3c0c32b188163e00310f5b39a293e29 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-32edc8920376aabb84ebe1900eaa9512d23f1b44d6459e4916dc6b07db66e27c
\ No newline at end of file
+87743ddef11749b4017d60abc297abfd673e02a26a2ae45ffec861327578aa30
\ No newline at end of file

diff --git a/src/alter.c b/src/alter.c
index c19eb67a67fd75350acc5e1077737b91c1b6f357..5c7ec996c7ca69678d432c6763e99f531ed22ffb 100644 (file)
--- a/src/alter.c
+++ b/src/alter.c
@@ -940,6 +940,14 @@ static void renameTokenFree(sqlite3 *db, RenameToken *pToken){
   }
 }
 
+/*
+** Return the RenameToken object associated with parse tree element pPtr,
+** or a NULL pointer if not found.  The RenameToken object returned is
+** removed from the list of RenameToken objects attached to the Parse
+** object and the caller becomes the new owner of the RenameToken object
+** Hence, the caller assumes responsibility for freeing the returned
+** RenameToken object.
+*/
 static RenameToken *renameTokenFind(Parse *pParse, void *pPtr){
   RenameToken **pp;
   for(pp=&pParse->pRename; (*pp); pp=&(*pp)->pNext){
@@ -953,6 +961,15 @@ static RenameToken *renameTokenFind(Parse *pParse, void *pPtr){
   return 0;
 }
 
+/*
+** This is a Walker expression callback.
+**
+** For every TK_COLUMN node in the expression tree, search to see
+** if the column being references is the column being renamed by an
+** ALTER TABLE statement.  If it is, then attach its associated
+** RenameToken object to the list of RenameToken objects being
+** constructed in RenameCtx object at pWalker->u.pRename.
+*/
 static int renameColumnExprCb(Walker *pWalker, Expr *pExpr){
   struct RenameCtx *p = pWalker->u.pRename;
   if( pExpr->op==TK_COLUMN && pExpr->iColumn==p->iCol ){
@@ -966,6 +983,15 @@ static int renameColumnExprCb(Walker *pWalker, Expr *pExpr){
   return WRC_Continue;
 }
 
+/*
+** The RenameCtx contains a list of tokens that reference a column that
+** is being renamed by an ALTER TABLE statement.  Return the "first"
+** RenameToken in the RenameCtx and remove that RenameToken from the
+** RenameContext.  "First" means the first RenameToken encountered when
+** the input SQL from left to right.  Repeated calls to this routine
+** return all column name tokens in the order that they are encountered
+** in the SQL statement.
+*/
 static RenameToken *renameColumnTokenNext(struct RenameCtx *pCtx){
   RenameToken *pBest = pCtx->pList;
   RenameToken *pToken;
@@ -981,7 +1007,24 @@ static RenameToken *renameColumnTokenNext(struct RenameCtx *pCtx){
 }
 
 /*
-** sqlite_rename_column(SQL, iCol, bQuote, zNew, zTable, zOld)
+** SQL function:
+**
+**     sqlite_rename_column(zSql, iCol, bQuote, zNew, zTable, zOld)
+**
+** Do a column rename operation on the CREATE statement given in zSql.
+** The iCol-th column (left-most is 0) of table zTable is renamed from zCol
+** into zNew.  The name should be quoted if bQuote is true.
+**
+** This function is used internally by the ALTER TABLE RENAME COLUMN command.
+** Though accessible to application code, it is not intended for use by
+** applications.  The existance of this function, and the way it works,
+** is subject to change without notice.
+**
+** If any of the parameters are out-of-bounds, then simply return NULL.
+** An out-of-bounds parameter can only occur when the application calls
+** this function directly.  The parameters will always be well-formed when
+** this routine is invoked by the bytecode for a legitimate ALTER TABLE
+** statement.
 */
 static void renameColumnFunc(
   sqlite3_context *context,
@@ -1009,8 +1052,13 @@ static void renameColumnFunc(
   int nQuot = 0;                  /* Length of zQuot in bytes */
   int i;
 
+  if( zSql==0 ) return;
+  if( zNew==0 ) return;
+  if( zTable==0 ) return;
+  if( zOld==0 ) return;
   memset(&sCtx, 0, sizeof(sCtx));
   sCtx.iCol = sqlite3_value_int(argv[1]);
+  if( sCtx.iCol<0 ) return;
 
   memset(&sParse, 0, sizeof(sParse));
   sParse.eParseMode = PARSE_MODE_RENAME_COLUMN;