Prevent stack overflow in json-related functions.

Sufficiently-deep recursion heretofore elicited a SIGSEGV.  If an
application constructs PostgreSQL json or jsonb values from arbitrary
user input, application users could have exploited this to terminate all
active database connections.  That applies to 9.3, where the json parser
adopted recursive descent, and later versions.  Only row_to_json() and
array_to_json() were at risk in 9.2, both in a non-security capacity.
Back-patch to 9.2, where the json type was introduced.

Oskari Saarenmaa, reviewed by Michael Paquier.

Security: CVE-2015-5289

9 files changed, 58 insertions, 0 deletions

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index eefe93bc8a..f394942bc3 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -490,6 +490,8 @@ parse_object(JsonLexContext *lex, JsonSemAction *sem)
 	json_struct_action oend = sem->object_end;
 	JsonTokenType tok;
 
+	check_stack_depth();
+
 	if (ostart != NULL)
 		(*ostart) (sem->semstate);
 
@@ -568,6 +570,8 @@ parse_array(JsonLexContext *lex, JsonSemAction *sem)
 	json_struct_action astart = sem->array_start;
 	json_struct_action aend = sem->array_end;
 
+	check_stack_depth();
+
 	if (astart != NULL)
 		(*astart) (sem->semstate);
 
@@ -1433,6 +1437,8 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 	char	   *outputstr;
 	text	   *jsontext;
 
+	check_stack_depth();
+
 	/* callers are expected to ensure that null keys are not passed in */
 	Assert(!(key_scalar && is_null));
 
diff --git a/src/backend/utils/adt/jsonb.c b/src/backend/utils/adt/jsonb.c
index f0f1651e9d..8fef35ea38 100644
--- a/src/backend/utils/adt/jsonb.c
+++ b/src/backend/utils/adt/jsonb.c
@@ -712,6 +712,8 @@ datum_to_jsonb(Datum val, bool is_null, JsonbInState *result,
 	JsonbValue	jb;
 	bool		scalar_jsonb = false;
 
+	check_stack_depth();
+
 	if (is_null)
 	{
 		Assert(!key_scalar);
diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 01b6bb0a48..f33864e619 100644
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -3724,6 +3724,8 @@ setPath(JsonbIterator **it, Datum *path_elems,
 	JsonbValue *res = NULL;
 	int			r;
 
+	check_stack_depth();
+
 	if (path_nulls[level])
 		elog(ERROR, "path element at the position %d is NULL", level + 1);
 
diff --git a/src/test/regress/expected/json.out b/src/test/regress/expected/json.out
index eb6b26b241..cb9a0a1eb3 100644
--- a/src/test/regress/expected/json.out
+++ b/src/test/regress/expected/json.out
@@ -231,6 +231,15 @@ LINE 1: SELECT '{"abc":1,3}'::json;
                ^
 DETAIL:  Expected string, but found "3".
 CONTEXT:  JSON data, line 1: {"abc":1,3...
+-- Recursion.
+SET max_stack_depth = '100kB';
+SELECT repeat('[', 1000)::json;
+ERROR:  stack depth limit exceeded
+HINT:  Increase the configuration parameter "max_stack_depth" (currently 100kB), after ensuring the platform's stack depth limit is adequate.
+SELECT repeat('{"a":', 1000)::json;
+ERROR:  stack depth limit exceeded
+HINT:  Increase the configuration parameter "max_stack_depth" (currently 100kB), after ensuring the platform's stack depth limit is adequate.
+RESET max_stack_depth;
 -- Miscellaneous stuff.
 SELECT 'true'::json;			-- OK
  json 
diff --git a/src/test/regress/expected/json_1.out b/src/test/regress/expected/json_1.out
index 48543e8c35..fe63a72b39 100644
--- a/src/test/regress/expected/json_1.out
+++ b/src/test/regress/expected/json_1.out
@@ -231,6 +231,15 @@ LINE 1: SELECT '{"abc":1,3}'::json;
                ^
 DETAIL:  Expected string, but found "3".
 CONTEXT:  JSON data, line 1: {"abc":1,3...
+-- Recursion.
+SET max_stack_depth = '100kB';
+SELECT repeat('[', 1000)::json;
+ERROR:  stack depth limit exceeded
+HINT:  Increase the configuration parameter "max_stack_depth" (currently 100kB), after ensuring the platform's stack depth limit is adequate.
+SELECT repeat('{"a":', 1000)::json;
+ERROR:  stack depth limit exceeded
+HINT:  Increase the configuration parameter "max_stack_depth" (currently 100kB), after ensuring the platform's stack depth limit is adequate.
+RESET max_stack_depth;
 -- Miscellaneous stuff.
 SELECT 'true'::json;			-- OK
  json 
diff --git a/src/test/regress/expected/jsonb.out b/src/test/regress/expected/jsonb.out
index 6da5a151d7..148364d74b 100644
--- a/src/test/regress/expected/jsonb.out
+++ b/src/test/regress/expected/jsonb.out
@@ -239,6 +239,15 @@ LINE 1: SELECT '{"abc":1,3}'::jsonb;
                ^
 DETAIL:  Expected string, but found "3".
 CONTEXT:  JSON data, line 1: {"abc":1,3...
+-- Recursion.
+SET max_stack_depth = '100kB';
+SELECT repeat('[', 1000)::jsonb;
+ERROR:  stack depth limit exceeded
+HINT:  Increase the configuration parameter "max_stack_depth" (currently 100kB), after ensuring the platform's stack depth limit is adequate.
+SELECT repeat('{"a":', 1000)::jsonb;
+ERROR:  stack depth limit exceeded
+HINT:  Increase the configuration parameter "max_stack_depth" (currently 100kB), after ensuring the platform's stack depth limit is adequate.
+RESET max_stack_depth;
 -- Miscellaneous stuff.
 SELECT 'true'::jsonb;			-- OK
  jsonb 
diff --git a/src/test/regress/expected/jsonb_1.out b/src/test/regress/expected/jsonb_1.out
index 39e7b1ff57..903dbd4c40 100644
--- a/src/test/regress/expected/jsonb_1.out
+++ b/src/test/regress/expected/jsonb_1.out
@@ -239,6 +239,15 @@ LINE 1: SELECT '{"abc":1,3}'::jsonb;
                ^
 DETAIL:  Expected string, but found "3".
 CONTEXT:  JSON data, line 1: {"abc":1,3...
+-- Recursion.
+SET max_stack_depth = '100kB';
+SELECT repeat('[', 1000)::jsonb;
+ERROR:  stack depth limit exceeded
+HINT:  Increase the configuration parameter "max_stack_depth" (currently 100kB), after ensuring the platform's stack depth limit is adequate.
+SELECT repeat('{"a":', 1000)::jsonb;
+ERROR:  stack depth limit exceeded
+HINT:  Increase the configuration parameter "max_stack_depth" (currently 100kB), after ensuring the platform's stack depth limit is adequate.
+RESET max_stack_depth;
 -- Miscellaneous stuff.
 SELECT 'true'::jsonb;			-- OK
  jsonb 
diff --git a/src/test/regress/sql/json.sql b/src/test/regress/sql/json.sql
index f631480f96..a173f06d95 100644
--- a/src/test/regress/sql/json.sql
+++ b/src/test/regress/sql/json.sql
@@ -45,6 +45,12 @@ SELECT '{"abc":1,"def":2,"ghi":[3,4],"hij":{"klm":5,"nop":[6]}}'::json; -- OK
 SELECT '{"abc":1:2}'::json;		-- ERROR, colon in wrong spot
 SELECT '{"abc":1,3}'::json;		-- ERROR, no value
 
+-- Recursion.
+SET max_stack_depth = '100kB';
+SELECT repeat('[', 1000)::json;
+SELECT repeat('{"a":', 1000)::json;
+RESET max_stack_depth;
+
 -- Miscellaneous stuff.
 SELECT 'true'::json;			-- OK
 SELECT 'false'::json;			-- OK
diff --git a/src/test/regress/sql/jsonb.sql b/src/test/regress/sql/jsonb.sql
index b1a0764cfa..f86b7fbf9b 100644
--- a/src/test/regress/sql/jsonb.sql
+++ b/src/test/regress/sql/jsonb.sql
@@ -48,6 +48,12 @@ SELECT '{"abc":1,"def":2,"ghi":[3,4],"hij":{"klm":5,"nop":[6]}}'::jsonb; -- OK
 SELECT '{"abc":1:2}'::jsonb;		-- ERROR, colon in wrong spot
 SELECT '{"abc":1,3}'::jsonb;		-- ERROR, no value
 
+-- Recursion.
+SET max_stack_depth = '100kB';
+SELECT repeat('[', 1000)::jsonb;
+SELECT repeat('{"a":', 1000)::jsonb;
+RESET max_stack_depth;
+
 -- Miscellaneous stuff.
 SELECT 'true'::jsonb;			-- OK
 SELECT 'false'::jsonb;			-- OK