CVE-2026-93235

Status: UPDATED  |  Advisory ID: CVE-2026-93235

Key Details

Affected Products, Subsystems & Sectors

What to Know

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. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References