refactor: improve edge case handling for recursion limits (backport #22988)

CHANGELOG.md

@@ -40,6 +40,10 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 Every module contains its own CHANGELOG.md. Please refer to the module you are interested in.
 
+### Improvements
+
+* (codec) [#22988](https://github.com/cosmos/cosmos-sdk/pull/22988) Improve edge case handling for recursion limits.
+
 ### Bug Fixes
 
 * (x/auth/tx) [#23148](https://github.com/cosmos/cosmos-sdk/pull/23148) Avoid panic from intoAnyV2 when v1.PublicKey is optional.

codec/types/interface_registry.go

@@ -274,10 +274,10 @@ func (r statefulUnpacker) cloneForRecursion() *statefulUnpacker {
 // UnpackAny deserializes a protobuf Any message into the provided interface, ensuring the interface is a pointer.
 // It applies stateful constraints such as max depth and call limits, and unpacks interfaces if required.
 func (r *statefulUnpacker) UnpackAny(any *Any, iface interface{}) error {
-	if r.maxDepth == 0 {
+	if r.maxDepth <= 0 {
 		return errors.New("max depth exceeded")
 	}
-	if r.maxCalls.count == 0 {
+	if r.maxCalls.count <= 0 {
 		return errors.New("call limit exceeded")
 	}
 	// here we gracefully handle the case in which `any` itself is `nil`, which may occur in message decoding

codec/unknownproto/unknown_fields.go

@@ -54,7 +54,7 @@ func doRejectUnknownFields(
 	if len(bz) == 0 {
 		return hasUnknownNonCriticals, nil
 	}
-	if recursionLimit == 0 {
+	if recursionLimit <= 0 {
 		return false, errors.New("recursion limit reached")
 	}