Bug 1220782 (CVE-2021-47066)

Summary: VUL-0: CVE-2021-47066: kernel: async_xor: incorrect source offset can lead to data corruption
Product: [Novell Products] SUSE Security Incidents Reporter: SMASH SMASH <smash_bz>
Component: IncidentsAssignee: Kernel Bugs <kernel-bugs>
Status: RESOLVED FIXED QA Contact: Security Team bot <security-team>
Severity: Normal    
Priority: P5 - None CC: carlos.lopez
Version: unspecified   
Target Milestone: ---   
Hardware: Other   
OS: Other   
URL: https://smash.suse.de/issue/395877/
Whiteboard: CVSSv3.1:SUSE:CVE-2021-47066:5.1:(AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H)
Found By: Security Response Team Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---

Description SMASH SMASH 2024-03-01 13:12:42 UTC 
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.

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-47066
https://git.kernel.org/stable/c/cab2e8e5997b592fdb7d02cf2387b4b8e3057174
https://git.kernel.org/stable/c/ceaf2966ab082bbc4d26516f97b3ca8a676e2af8
https://www.cve.org/CVERecord?id=CVE-2021-47066
https://git.kernel.org/stable/c/29ffa50f33de824b5491f8239c88c4a0efdd03af
https://git.kernel.org/stable/c/53f8208e11abd6dde9480dfcb97fecdb1bc2ac18
https://bugzilla.redhat.com/show_bug.cgi?id=2267162
Comment 1 Carlos López 2024-03-01 13:13:29 UTC 
Already fixed in cve/linux-5.14 and newer. Older branches not affected. Closing.