CVE-2021-47460

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

ocfs2: fix data corruption after conversion from inline format

Commit 6dbf7bb55598 ("fs: Don't invalidate page buffers in

block_write_full_page()") uncovered a latent bug in ocfs2 conversion

from inline inode format to a normal inode format.

The code in ocfs2_convert_inline_data_to_extents() attempts to zero out

the whole cluster allocated for file data by grabbing, zeroing, and

dirtying all pages covering this cluster. However these pages are

beyond i_size, thus writeback code generally ignores these dirty pages

and no blocks were ever actually zeroed on the disk.

This oversight was fixed by commit 693c241a5f6a ("ocfs2: No need to zero

pages past i_size.") for standard ocfs2 write path, inline conversion

path was apparently forgotten; the commit log also has a reasoning why

the zeroing actually is not needed.

After commit 6dbf7bb55598, things became worse as writeback code stopped

invalidating buffers on pages b

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References