A NULL pointer dereference flaw was found in the Linux kernel"s SELinux subsystem in versions before 5.7. This flaw occurs while importing the Commercial IP Security Option protocol"s category bitmap into the SELinux extensible bitmap via the" ebitmap_netlbl_import" routine. While processing the CIPSO restricted bitmap tag in the "cipso_v4_parsetag_rbm" routine, it sets the security attribute to indicate that the category bitmap is present, even if it has not been allocated. This issue leads to a NULL pointer dereference issue while importing the same category bitmap into SELinux. This flaw allows a remote network user to crash the system kernel, resulting in a denial of service. An issue was discovered in the Linux kernel before 5.6.5. There is a use-after-free in block/bfq-iosched.c related to bfq_idle_slice_timer_body. A signal access-control issue was discovered in the Linux kernel before 5.6.5, aka CID-7395ea4e65c2. Because exec_id in include/linux/sched.h is only 32 bits, an integer overflow can interfere with a do_notify_parent protection mechanism. A child process can send an arbitrary signal to a parent process in a different security domain. Exploitation limitations include the amount of elapsed time before an integer overflow occurs, and the lack of scenarios where signals to a parent process present a substantial operational threat