CVE-2021-47066: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: async_xor: increase src_offs when dropping destination page Now we support sharing one page if PAGE_SIZE is not equal stripe size. To support this, it needs to support calculating xor value with different offsets for each r5dev. One offset array is used to record those offsets. In RMW mode, parity page is used as a source page. It sets ASYNC_TX_XOR_DROP_DST before calculating xor value in ops_run_prexor5. So it needs to add src_list and src_offs at the same time. Now it only needs src_list. So the xor value which is calculated is wrong. It can cause data corruption problem. I can reproduce this problem 100% on a POWER8 machine. The steps are: mdadm -CR /dev/md0 -l5 -n3 /dev/sdb1 /dev/sdc1 /dev/sdd1 --size=3G mkfs.xfs /dev/md0 mount /dev/md0 /mnt/test mount: /mnt/test: mount(2) system call failed: Structure needs cleaning.

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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	Versions
linux	linux_kernel	5.10 — 5.10.37
linux	linux_kernel	5.11 — 5.11.21
linux	linux_kernel	5.12 — 5.12.4

References

Advisories & Patches

https://git.kernel.org/stable/c/29ffa50f33de824b5491f8239c88c4a0efdd03af https://git.kernel.org/stable/c/53f8208e11abd6dde9480dfcb97fecdb1bc2ac18 https://git.kernel.org/stable/c/cab2e8e5997b592fdb7d02cf2387b4b8e3057174 https://git.kernel.org/stable/c/ceaf2966ab082bbc4d26516f97b3ca8a676e2af8 https://git.kernel.org/stable/c/29ffa50f33de824b5491f8239c88c4a0efdd03af https://git.kernel.org/stable/c/53f8208e11abd6dde9480dfcb97fecdb1bc2ac18 https://git.kernel.org/stable/c/cab2e8e5997b592fdb7d02cf2387b4b8e3057174 https://git.kernel.org/stable/c/ceaf2966ab082bbc4d26516f97b3ca8a676e2af8

Frequently Asked Questions

What is CVE-2021-47066? +

In the Linux kernel, the following vulnerability has been resolved: async_xor: increase src_offs when dropping destination page Now we support sharing one page if PAGE_SIZE is not equal stripe size. To support this, it needs to support calculating xor value with different offsets for each r5dev. One offset array is used to record those offsets. In RMW mode, parity page is used as a source page. It sets ASYNC_TX_XOR_DROP_DST before calculating xor value in ops_run_prexor5. So it needs to add src_list and src_offs at the same time. Now it only needs src_list. So the xor value which is calculated is wrong. It can cause data corruption problem. I can reproduce this problem 100% on a POWER8 machine. The steps are: mdadm -CR /dev/md0 -l5 -n3 /dev/sdb1 /dev/sdc1 /dev/sdd1 --size=3G mkfs.xfs /dev/md0 mount /dev/md0 /mnt/test mount: /mnt/test: mount(2) system call failed: Structure needs cleaning. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-47066? +

CVE-2021-47066 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-2021-47066? +

CVE-2021-47066 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-2021-47066? +

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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CVE-2021-47066