Fix infinite loop in cache loop detection algorithm

Signed-off-by: Israel Barbosa <[email protected]>

Author: Israel Barbosa

cache/remotecache/v1/utils.go

@@ -133,14 +133,19 @@ func (s *normalizeState) removeLoops(ctx context.Context) {
 		}
 	}
 
-	visited := map[digest.Digest]struct{}{}
+	globalVisited := map[digest.Digest]struct{}{}
 
 	for _, d := range roots {
-		s.checkLoops(ctx, d, visited)
+		if _, ok := globalVisited[d]; ok {
+			continue
+		}
+
+		visited := map[digest.Digest]struct{}{}
+		s.checkLoops(ctx, d, visited, globalVisited)
 	}
 }
 
-func (s *normalizeState) checkLoops(ctx context.Context, d digest.Digest, visited map[digest.Digest]struct{}) {
+func (s *normalizeState) checkLoops(ctx context.Context, d digest.Digest, visited map[digest.Digest]struct{}, globalVisited map[digest.Digest]struct{}) {
 	it, ok := s.byKey[d]
 	if !ok {
 		return
@@ -149,7 +154,13 @@ func (s *normalizeState) checkLoops(ctx context.Context, d digest.Digest, visite
 	if !ok {
 		return
 	}
+
+	if _, ok := globalVisited[d]; ok {
+		return
+	}
+
 	visited[d] = struct{}{}
+	globalVisited[d] = struct{}{}
 	defer func() {
 		delete(visited, d)
 	}()
@@ -166,7 +177,7 @@ func (s *normalizeState) checkLoops(ctx context.Context, d digest.Digest, visite
 				}
 				delete(links[l], id)
 			} else {
-				s.checkLoops(ctx, id, visited)
+				s.checkLoops(ctx, id, visited, globalVisited)
 			}
 		}
 	}