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Date: Fri, 15 Mar 2024 21:15:04 +0100
From: Greg Kroah-Hartman <>
Cc: Greg Kroah-Hartman <>
Subject: CVE-2021-47114: ocfs2: fix data corruption by fallocate


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

ocfs2: fix data corruption by fallocate

When fallocate punches holes out of inode size, if original isize is in
the middle of last cluster, then the part from isize to the end of the
cluster will be zeroed with buffer write, at that time isize is not yet
updated to match the new size, if writeback is kicked in, it will invoke
ocfs2_writepage()->block_write_full_page() where the pages out of inode
size will be dropped.  That will cause file corruption.  Fix this by
zero out eof blocks when extending the inode size.

Running the following command with qemu-image 4.2.1 can get a corrupted
coverted image file easily.

    qemu-img convert -p -t none -T none -f qcow2 $qcow_image \
             -O qcow2 -o compat=1.1 $qcow_image.conv

The usage of fallocate in qemu is like this, it first punches holes out
of inode size, then extend the inode size.

    fallocate(11, FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE, 2276196352, 65536) = 0
    fallocate(11, 0, 2276196352, 65536) = 0


The Linux kernel CVE team has assigned CVE-2021-47114 to this issue.

Affected and fixed versions

	Fixed in 4.4.272 with commit 624fa7baa378
	Fixed in 4.9.272 with commit 33e03adafb29
	Fixed in 4.14.236 with commit a1700479524b
	Fixed in 4.19.194 with commit cec4e857ffaa
	Fixed in 5.4.125 with commit cc2edb99ea60
	Fixed in 5.10.43 with commit c8d5faee4624
	Fixed in 5.12.10 with commit 0a31dd6fd2f4
	Fixed in 5.13 with commit 6bba4471f0cc

Please see or a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files

The file(s) affected by this issue are:


The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:

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