CVE-2023-53231CVE-2023-53231

In the Linux kernel, the following vulnerability has been resolved: erofs: Fix detection of atomic context Current check for atomic context is not sufficient as z_erofs_decompressqueue_endio can be called under rcu lock from blk_mq_flush_plug_list(). See the stacktrace [1] In such case we should hand off the decompression work for async processing rather than trying to do sync decompression in current context. Patch fixes the detection by checking for rcu_read_lock_any_held() and while at it use more appropriate !in_task() check than in_atomic(). Background: Historically erofs would always schedule a kworker for decompression which would incur the scheduling cost regardless of the context. But z_erofs_decompressqueue_endio() may not always be in atomic context and we could actually benefit from doing the decompression in z_erofs_decompressqueue_endio() if we are in thread context, for example when running with dm-verity. This optimization was later added in patch [2] which has show