From 676691ce6d5eb4f400612529b02cdb87cc33bda1 Mon Sep 17 00:00:00 2001
From: Milos Gajdos <milosthegajdos@gmail.com>
Date: Fri, 28 Jan 2022 10:54:07 +0000
Subject: [PATCH] Fix: Avoid a false type assertion in the inmemory driver

This issue was discovered by the following fuzzer:
https://github.com/cncf/cncf-fuzzing/blob/main/projects/distribution/inmemory_fuzzer.go#L24

Signed-off-by: Milos Gajdos <milosthegajdos@gmail.com>
---
 registry/storage/driver/inmemory/mfs.go | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/registry/storage/driver/inmemory/mfs.go b/registry/storage/driver/inmemory/mfs.go
index 9a2865f95..8134e1cce 100644
--- a/registry/storage/driver/inmemory/mfs.go
+++ b/registry/storage/driver/inmemory/mfs.go
@@ -244,11 +244,16 @@ func (d *dir) delete(p string) error {
 		return errNotExists
 	}
 
-	if _, ok := parent.(*dir).children[filename]; !ok {
+	parentDir, ok := parent.(*dir)
+	if !ok {
+		return errIsNotDir
+	}
+
+	if _, ok := parentDir.children[filename]; !ok {
 		return errNotExists
 	}
 
-	delete(parent.(*dir).children, filename)
+	delete(parentDir.children, filename)
 	return nil
 }