CVE-2021-47114 Affecting kernel-source package, versions <5.3.18-150200.24.188.1


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.04% (15th percentile)

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  • Snyk IDSNYK-SLES152-KERNELSOURCE-6690978
  • published29 Apr 2024
  • disclosed26 Apr 2024

Introduced: 26 Apr 2024

CVE-2021-47114  (opens in a new tab)

How to fix?

Upgrade SLES:15.2 kernel-source to version 5.3.18-150200.24.188.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-source package and not the kernel-source package as distributed by SLES. See How to fix? for SLES:15.2 relevant fixed versions and status.

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/20210525093034.GB4112@quack2.suse.cz/T/

CVSS Scores

version 3.1