CVE-2023-53172

Description

In the Linux kernel, the following vulnerability has been resolved: fsverity: reject FS_IOC_ENABLE_VERITY on mode 3 fds Commit 56124d6c87fd ("fsverity: support enabling with tree block size < PAGE_SIZE") changed FS_IOC_ENABLE_VERITY to use __kernel_read() to read the file's data, instead of direct pagecache accesses. An unintended consequence of this is that the 'WARN_ON_ONCE(!(file->f_mode & FMODE_READ))' in __kernel_read() became reachable by fuzz tests. This happens if FS_IOC_ENABLE_VERITY is called on a fd opened with access mode 3, which means "ioctl access only". Arguably, FS_IOC_ENABLE_VERITY should work on ioctl-only fds. But ioctl-only fds are a weird Linux extension that is rarely used and that few people even know about. (The documentation for FS_IOC_ENABLE_VERITY even specifically says it requires O_RDONLY.) It's probably not worthwhile to make the ioctl internally open a new fd just to handle this case. Thus, just reject the ioctl on such fds for now.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

References

• https://git.kernel.org/stable/c/85c039cff3c359967cafe90443c02321e950b216 ↗
• https://git.kernel.org/stable/c/04839139213cf60d4c5fc792214a08830e294ff8 ↗