From RhBug:1970273

An out-of-bounds write flaw was found in the seq_file in Filesystem layer, where a local attacker with a user privilege could gain access to out-of-bound memory leading to a system crash or a leak of internal kernel information. The issue results from not validating the size_t-to-int conversion prior to performing operations. The highest threat from this vulnerability is to data integrity, confidentiality and system availability.

While 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.

Reference fixes:

• Upstream fix: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8cae8cd89f05f6de223d63e6d15e31c8ba9cf53b