CVE-2021-47114

MEDIUM
Published Mar 15, 2024 Modified Apr 4, 2025

Description

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 v1: https://www.spinics.net/lists/linux-fsdevel/msg193999.html v2: https://lore.kernel.org/linux-fsdevel/[email protected]/T/

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CVSS v3.1 Score

5.5
MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected Products

Vendor Product
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel

References

Advisories & Patches

https://git.kernel.org/stable/c/0a31dd6fd2f4e7db538fb6eb1f06973d81f8dd3b https://git.kernel.org/stable/c/33e03adafb29eedae1bae9cdb50c1385279fcf65 https://git.kernel.org/stable/c/624fa7baa3788dc9e57840ba5b94bc22b03cda57 https://git.kernel.org/stable/c/6bba4471f0cc1296fe3c2089b9e52442d3074b2e https://git.kernel.org/stable/c/a1700479524bb9cb5e8ae720236a6fabd003acae https://git.kernel.org/stable/c/c8d5faee46242c3f33b8a71a4d7d52214785bfcc https://git.kernel.org/stable/c/cc2edb99ea606a45182b5ea38cc8f4e583aa0774 https://git.kernel.org/stable/c/cec4e857ffaa8c447f51cd8ab4e72350077b6770 https://git.kernel.org/stable/c/0a31dd6fd2f4e7db538fb6eb1f06973d81f8dd3b https://git.kernel.org/stable/c/33e03adafb29eedae1bae9cdb50c1385279fcf65 https://git.kernel.org/stable/c/624fa7baa3788dc9e57840ba5b94bc22b03cda57 https://git.kernel.org/stable/c/6bba4471f0cc1296fe3c2089b9e52442d3074b2e https://git.kernel.org/stable/c/a1700479524bb9cb5e8ae720236a6fabd003acae https://git.kernel.org/stable/c/c8d5faee46242c3f33b8a71a4d7d52214785bfcc https://git.kernel.org/stable/c/cc2edb99ea606a45182b5ea38cc8f4e583aa0774 https://git.kernel.org/stable/c/cec4e857ffaa8c447f51cd8ab4e72350077b6770

Frequently Asked Questions

What is CVE-2021-47114? +
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 v1: https://www.spinics.net/lists/linux-fsdevel/msg193999.html v2: https://lore.kernel.org/linux-fsdevel/[email protected]/T/ It has a CVSS v3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2021-47114? +
CVE-2021-47114 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.
What products are affected by CVE-2021-47114? +
CVE-2021-47114 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2021-47114? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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