From: Javid Khan <dxbjavid@gmail.com>
Date: Sat, 27 Jun 2026 17:22:43 +0000 (+0530)
Subject: fix signed overflow negating INT64_MIN in json_object_int_inc
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=54f55260115bb91ecb973381bc1038167808e105;p=thirdparty%2Fjson-c.git

fix signed overflow negating INT64_MIN in json_object_int_inc
---

diff --git a/json_object.c b/json_object.c
index 0a61967..4c6db9b 100644
--- a/json_object.c
+++ b/json_object.c
@@ -1113,14 +1113,14 @@ int json_object_int_inc(struct json_object *jso, int64_t val)
 		{
 			jsoint->cint.c_uint64 = UINT64_MAX;
 		}
-		else if (val < 0 && jsoint->cint.c_uint64 < (uint64_t)(-val))
+		else if (val < 0 && jsoint->cint.c_uint64 < (0 - (uint64_t)val))
 		{
 			jsoint->cint.c_int64 = (int64_t)jsoint->cint.c_uint64 + val;
 			jsoint->cint_type = json_object_int_type_int64;
 		}
-		else if (val < 0 && jsoint->cint.c_uint64 >= (uint64_t)(-val))
+		else if (val < 0 && jsoint->cint.c_uint64 >= (0 - (uint64_t)val))
 		{
-			jsoint->cint.c_uint64 -= (uint64_t)(-val);
+			jsoint->cint.c_uint64 -= (0 - (uint64_t)val);
 		}
 		else
 		{
diff --git a/tests/test_int_add.c b/tests/test_int_add.c
index 142feac..be3f5c0 100644
--- a/tests/test_int_add.c
+++ b/tests/test_int_add.c
@@ -68,6 +68,17 @@ int main(int argc, char **argv)
 	assert(json_object_get_uint64(tmp) == 0);
 	json_object_put(tmp);
 	printf("UINT64 ADD UNDERFLOW PASSED\n");
+	// Decrement by INT64_MIN: -val would overflow int64_t, so the magnitude
+	// has to be taken in unsigned space.
+	tmp = json_object_new_uint64(100);
+	json_object_int_inc(tmp, INT64_MIN);
+	assert(json_object_get_int64(tmp) == INT64_MIN + 100);
+	json_object_put(tmp);
+	tmp = json_object_new_uint64(UINT64_MAX);
+	json_object_int_inc(tmp, INT64_MIN);
+	assert(json_object_get_uint64(tmp) == (uint64_t)INT64_MAX);
+	json_object_put(tmp);
+	printf("UINT64 ADD INT64_MIN PASSED\n");
 
 	printf("PASSED\n");
 	return 0;
diff --git a/tests/test_int_add.expected b/tests/test_int_add.expected
index f9348d4..34b8edf 100644
--- a/tests/test_int_add.expected
+++ b/tests/test_int_add.expected
@@ -7,4 +7,5 @@ INT64 ADD UNDERFLOW PASSED
 UINT64 ADD PASSED
 UINT64 ADD OVERFLOW PASSED
 UINT64 ADD UNDERFLOW PASSED
+UINT64 ADD INT64_MIN PASSED
 PASSED