From c7c2cc67007741338a36a8d7aa86e23600aa5e18 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 19 Jan 2020 19:15:15 -0500
Subject: [PATCH] Fix out-of-memory handling in ecpglib.

ecpg_build_params() would crash on a null pointer dereference if
realloc() failed, due to updating the persistent "stmt" struct
too aggressively.  (Even without the crash, this would've leaked
the old storage that we were trying to realloc.)

Per Coverity.  This seems to have been broken in commit 0cc050794,
so back-patch into v12.
---
 src/interfaces/ecpg/ecpglib/execute.c | 37 +++++++++++++++++----------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/src/interfaces/ecpg/ecpglib/execute.c b/src/interfaces/ecpg/ecpglib/execute.c
index 0912d87c77..606aff6373 100644
--- a/src/interfaces/ecpg/ecpglib/execute.c
+++ b/src/interfaces/ecpg/ecpglib/execute.c
@@ -1502,26 +1502,37 @@ ecpg_build_params(struct statement *stmt)
 		}
 		else
 		{
-			if (!(stmt->paramvalues = (char **) ecpg_realloc(stmt->paramvalues, sizeof(char *) * (stmt->nparams + 1), stmt->lineno)))
+			bool		realloc_failed = false;
+			char	  **newparamvalues;
+			int		   *newparamlengths;
+			int		   *newparamformats;
+
+			/* enlarge all the param arrays */
+			if ((newparamvalues = (char **) ecpg_realloc(stmt->paramvalues, sizeof(char *) * (stmt->nparams + 1), stmt->lineno)))
+				stmt->paramvalues = newparamvalues;
+			else
+				realloc_failed = true;
+
+			if ((newparamlengths = (int *) ecpg_realloc(stmt->paramlengths, sizeof(int) * (stmt->nparams + 1), stmt->lineno)))
+				stmt->paramlengths = newparamlengths;
+			else
+				realloc_failed = true;
+
+			if ((newparamformats = (int *) ecpg_realloc(stmt->paramformats, sizeof(int) * (stmt->nparams + 1), stmt->lineno)))
+				stmt->paramformats = newparamformats;
+			else
+				realloc_failed = true;
+
+			if (realloc_failed)
 			{
 				ecpg_free_params(stmt, false);
 				ecpg_free(tobeinserted);
 				return false;
 			}
+
+			/* only now can we assign ownership of "tobeinserted" to stmt */
 			stmt->paramvalues[stmt->nparams] = tobeinserted;
-
-			if (!(stmt->paramlengths = (int *) ecpg_realloc(stmt->paramlengths, sizeof(int) * (stmt->nparams + 1), stmt->lineno)))
-			{
-				ecpg_free_params(stmt, false);
-				return false;
-			}
 			stmt->paramlengths[stmt->nparams] = binary_length;
-
-			if (!(stmt->paramformats = (int *) ecpg_realloc(stmt->paramformats, sizeof(int) * (stmt->nparams + 1), stmt->lineno)))
-			{
-				ecpg_free_params(stmt, false);
-				return false;
-			}
 			stmt->paramformats[stmt->nparams] = (binary_format ? 1 : 0);
 			stmt->nparams++;