CVE-2021-47114

Summary

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/

Affected Software

VendorProductVersion RangeStatus
LinuxLinux385820a38d5e7c70b20af4d68767b1920b1e4133 < 624fa7baa3788dc9e57840ba5b94bc22b03cda57affected
LinuxLinux385820a38d5e7c70b20af4d68767b1920b1e4133 < 33e03adafb29eedae1bae9cdb50c1385279fcf65affected
LinuxLinux385820a38d5e7c70b20af4d68767b1920b1e4133 < a1700479524bb9cb5e8ae720236a6fabd003acaeaffected
LinuxLinux385820a38d5e7c70b20af4d68767b1920b1e4133 < cec4e857ffaa8c447f51cd8ab4e72350077b6770affected
LinuxLinux385820a38d5e7c70b20af4d68767b1920b1e4133 < cc2edb99ea606a45182b5ea38cc8f4e583aa0774affected
LinuxLinux385820a38d5e7c70b20af4d68767b1920b1e4133 < c8d5faee46242c3f33b8a71a4d7d52214785bfccaffected
LinuxLinux385820a38d5e7c70b20af4d68767b1920b1e4133 < 0a31dd6fd2f4e7db538fb6eb1f06973d81f8dd3baffected
LinuxLinux385820a38d5e7c70b20af4d68767b1920b1e4133 < 6bba4471f0cc1296fe3c2089b9e52442d3074b2eaffected
LinuxLinux2.6.23affected
LinuxLinux0 < 2.6.23unaffected
LinuxLinux4.4.272 <= 4.4.*unaffected
LinuxLinux4.9.272 <= 4.9.*unaffected
LinuxLinux4.14.236 <= 4.14.*unaffected
LinuxLinux4.19.194 <= 4.19.*unaffected
LinuxLinux5.4.125 <= 5.4.*unaffected
LinuxLinux5.10.43 <= 5.10.*unaffected
LinuxLinux5.12.10 <= 5.12.*unaffected
LinuxLinux5.13 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

CVE Program Container

Additional References

References