A Linux kernel vulnerability (CVE-2022-2590) has been identified that allows unprivileged users to modify memory-mapped files (mmap) and tmpfs files without write permissions, thus elevating their privileges within the system. The nature of this issue resembles the Dirty COW vulnerability, but it is restricted to affecting data in shared memory (shmem/tmpfs). This issue can also be exploited to modify running executable files that use shared memory.
The problem is caused by a race condition in the memory management subsystem, which occurs when handling an exception (fault) generated when attempting to write to read-only regions in shared memory mapped in COW (copy-on-write mapping) mode. The issue manifests from kernel version 5.16 on x86-64 and aarch64 systems compiled with the CONFIG_USERFAULTFD=y option. The vulnerability has been fixed in release 5.19. A proof-of-concept exploit is scheduled for publication on August 15.
Forrás: opennet.ru
