Fix integer-overflow problem in intarray's g_int_decompress().

An array element equal to INT_MAX gave this code indigestion,
causing an infinite loop that surely ended in SIGSEGV.  We fixed
some nearby problems awhile ago (cf 757c5182f) but missed this.

Report and diagnosis by Alexander Lakhin (bug #18273); patch by me

Discussion: https://postgr.es/m/18273-9a832d1da122600c@postgresql.org

4 files changed, 27 insertions, 22 deletions

diff --git a/contrib/intarray/_int_gist.c b/contrib/intarray/_int_gist.c
index ea79c4bb51f..5d46b6bc13e 100644
--- a/contrib/intarray/_int_gist.c
+++ b/contrib/intarray/_int_gist.c
@@ -296,8 +296,7 @@ g_int_decompress(PG_FUNCTION_ARGS)
 	ArrayType  *in;
 	int			lenin;
 	int		   *din;
-	int			i,
-				j;
+	int			i;
 
 	in = DatumGetArrayTypeP(entry->key);
 
@@ -341,9 +340,12 @@ g_int_decompress(PG_FUNCTION_ARGS)
 	dr = ARRPTR(r);
 
 	for (i = 0; i < lenin; i += 2)
-		for (j = din[i]; j <= din[i + 1]; j++)
+	{
+		/* use int64 for j in case din[i + 1] is INT_MAX */
+		for (int64 j = din[i]; j <= din[i + 1]; j++)
 			if ((!i) || *(dr - 1) != j)
-				*dr++ = j;
+				*dr++ = (int) j;
+	}
 
 	if (in != (ArrayType *) DatumGetPointer(entry->key))
 		pfree(in);
diff --git a/contrib/intarray/data/test__int.data b/contrib/intarray/data/test__int.data
index b3903d0f33a..0a7fac3c087 100644
--- a/contrib/intarray/data/test__int.data
+++ b/contrib/intarray/data/test__int.data
@@ -6998,3 +6998,4 @@
 {173,208,229}
 {6,22,142,267,299}
 {22,122,173,245,293}
+{1,2,101,102,201,202,2147483647}
diff --git a/contrib/intarray/expected/_int.out b/contrib/intarray/expected/_int.out
index 2f33c7e18d5..09ab23483f7 100644
--- a/contrib/intarray/expected/_int.out
+++ b/contrib/intarray/expected/_int.out
@@ -464,13 +464,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 SET enable_seqscan = off;  -- not all of these would use index by default
@@ -538,13 +538,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 INSERT INTO test__int SELECT array(SELECT x FROM generate_series(1, 1001) x); -- should fail
@@ -620,13 +620,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 DROP INDEX text_idx;
@@ -700,13 +700,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 DROP INDEX text_idx;
@@ -774,13 +774,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 DROP INDEX text_idx;
@@ -848,13 +848,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 DROP INDEX text_idx;
@@ -870,9 +870,10 @@ DROP INDEX text_idx;
 -- core that would reach the same codepaths.
 CREATE TABLE more__int AS SELECT
    -- Leave alone NULLs, empty arrays and the one row that we use to test
-   -- equality
+   -- equality; also skip INT_MAX
    CASE WHEN a IS NULL OR a = '{}' OR a = '{73,23,20}' THEN a ELSE
-     (select array_agg(u) || array_agg(u + 1000) || array_agg(u + 2000) from (select unnest(a) u) x)
+     (select array_agg(u) || array_agg(u + 1000) || array_agg(u + 2000)
+      from unnest(a) u where u < 2000000000)
    END AS a, a as b
    FROM test__int;
 CREATE INDEX ON more__int using gist (a gist__int_ops(numranges = 252));
@@ -939,13 +940,13 @@ SELECT count(*) from more__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from more__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from more__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 RESET enable_seqscan;
diff --git a/contrib/intarray/sql/_int.sql b/contrib/intarray/sql/_int.sql
index bd3e01208d5..95eec96c14e 100644
--- a/contrib/intarray/sql/_int.sql
+++ b/contrib/intarray/sql/_int.sql
@@ -194,9 +194,10 @@ DROP INDEX text_idx;
 -- core that would reach the same codepaths.
 CREATE TABLE more__int AS SELECT
    -- Leave alone NULLs, empty arrays and the one row that we use to test
-   -- equality
+   -- equality; also skip INT_MAX
    CASE WHEN a IS NULL OR a = '{}' OR a = '{73,23,20}' THEN a ELSE
-     (select array_agg(u) || array_agg(u + 1000) || array_agg(u + 2000) from (select unnest(a) u) x)
+     (select array_agg(u) || array_agg(u + 1000) || array_agg(u + 2000)
+      from unnest(a) u where u < 2000000000)
    END AS a, a as b
    FROM test__int;
 CREATE INDEX ON more__int using gist (a gist__int_ops(numranges = 252));