LibC: Validate the len argument for inet_ntop()

Author: https://github.com/gunnarbeutner
Commit: 287a93a2a4
Pull-request: https://github.com/SerenityOS/serenity/pull/6281

Userland/Libraries/LibC/arpa/inet.cpp

@@ -37,6 +37,10 @@ const char* inet_ntop(int af, const void* src, char* dst, socklen_t len)
         errno = EAFNOSUPPORT;
         return nullptr;
     }
+    if (len < 4) {
+        errno = ENOSPC;
+        return nullptr;
+    }
     auto* bytes = (const unsigned char*)src;
     snprintf(dst, len, "%u.%u.%u.%u", bytes[0], bytes[1], bytes[2], bytes[3]);
     return (const char*)dst;