Inspektor Gadget Uprobe gadgets: unprivileged container's ld.so.cache causes high CPU utilization and container startup DoS

Inspektor Gadget is a set of tools and framework for data collection and system inspection on Kubernetes clusters and Linux hosts using eBPF. From 0.27.0 until 0.53.1, the uprobe library resolver can allow an unprivileged container to consume excessive CPU and block other containers from starting by supplying a crafted /etc/ld.so.cache file while an uprobe-based gadget is active. The parser in pkg/uprobetracer/ldcache_parser.go trusts EntryCount enough to perform excessive iteration, computes cache1Len with overflowing uint32 arithmetic, and repeatedly calls readStringFromBytes in pkg/uprobetracer/bytes.go, where byte-by-byte immutable string concatenation produces quadratic work. While this processing occurs, pkg/container-hook holds the fanotify container-start pause, allowing a crafted cache to delay startup for roughly a minute, prevent Docker from starting other containers, and degrade monitoring. Processing caches from already-running containers can still consume CPU but does not hold the new-container startup pause, and the advisory establishes no confidentiality or integrity impact. This issue is fixed in version 0.53.1.