Sequoia: A deep root in Linux's filesystem layer (CVE-2021-33909)

Qualys security advisory about a size_t-to-int conversion vulnerability in the Linux kernel's filesystem layer.

By creating, mounting, and deleting a deep directory structure whose total path length exceeds 1GB, an unprivileged local attacker can write the 10-byte string "//deleted" to an offset of exactly -2GB-10B below the beginning of a vmalloc()ated kernel buffer.

Report: https://www.openwall.com/lists/oss-security/2021/07/20/1