CVE-2026-53015
Description
In the Linux kernel, the following vulnerability has been resolved:
erofs: unify lcn as u64 for 32-bit platforms
As sashiko reported [1], `lcn` was typed as `unsigned long` (or
`unsigned int` sometimes), which is only 32 bits wide on 32-bit
platforms, which causes `(lcn << lclusterbits)` to be truncated
at 4 GiB.
In order to consolidate the logic, just use `u64` consistently
around the codebase.
[1] https://sashiko.dev/r/20260420034612.1899973-1-hsiangkao%40linux.alibaba.com
Summary dbcve.org
In the Linux kernel's erofs filesystem, the logical cluster number (lcn) variable was incorrectly typed as `unsigned long` or `unsigned int`, which is only 32 bits wide on 32-bit platforms. When performing `(lcn << lclusterbits)` to calculate cluster offsets, the result gets truncated at 4 GiB, potentially causing incorrect data access or file system corruption when handling files/clusters beyond 4 GiB on 32-bit systems.
Mitigation
This is a kernel bug fix requiring a type change from 32-bit to 64-bit (u64). No end-user mitigation is available; organizations should apply kernel updates when available.