CVE-2021-47066 async_xor: increase src_offs when dropping destination page
A logic error in the Linux kernel's async_xor function causes data corruption during RAID5 operations, requiring a kernel patch.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-47066?
CVE-2021-47066 is a high-severity vulnerability in Linux kernel, published on 29 Feb 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2021-47066?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47066?
Apply the vendor's patch.
Is CVE-2021-47066 being exploited?
There is no known exploitation of CVE-2021-47066 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47066, GHSA-f2cq-j285-crf8, UBUNTU-CVE-2021-47066.