Linux Kernel Directory Offset Vulnerability in 32-Bit Systems

A vulnerability in the Linux kernel's directory offset allocation mechanism can lead to persistent loss of directory entries on 32-bit systems. The issue arises when the offset allocator wraps around to a low value, causing existing directory entries to become invisible during readdir operations. This problem was introduced by a commit that incorrectly treated directory offsets as monotonically increasing integers, rather than opaque cookies, leading to a permanent disappearance of certain entries from readdir output.

Impact

The vulnerability causes directory entries to vanish persistently from readdir output on 32-bit systems, creating a loss of visibility for those entries during directory read operations.