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.

diff --git a/src/interfaces/ecpg/ecpglib/execute.c b/src/interfaces/ecpg/ecpglib/execute.c
index e261cf916714d7240de10beab1aa35da1d7d5059..59e8e3a8258bc2f804ae7c522b7c5f994741cf2d 100644 (file)
--- a/src/interfaces/ecpg/ecpglib/execute.c
+++ b/src/interfaces/ecpg/ecpglib/execute.c
@@ -1499,26 +1499,37 @@ 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;
                        }
-                       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;
-                       }
+                       /* only now can we assign ownership of "tobeinserted" to stmt */
+                       stmt->paramvalues[stmt->nparams] = tobeinserted;
                        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++;