CVE-2021-47227
- Source
- https://nvd.nist.gov/vuln/detail/CVE-2021-47227
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-47227.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2021-47227
- Related
- Published
- 2024-05-21T15:15:11Z
- Modified
- 2024-09-18T01:00:20Z
- Summary
- [none]
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
x86/fpu: Prevent state corruption in fpurestore_sig()
The non-compacted slowpath uses _copyfromuser() and copies the entire user buffer into the kernel buffer, verbatim. This means that the kernel buffer may now contain entirely invalid state on which XRSTOR will #GP. validateuserxstateheader() can detect some of that corruption, but that leaves the onus on callers to clear the buffer.
Prior to XSAVES support, it was possible just to reinitialize the buffer, completely, but with supervisor states that is not longer possible as the buffer clearing code split got it backwards. Fixing that is possible but not corrupting the state in the first place is more robust.
Avoid corruption of the kernel XSAVE buffer by using copyusertoxstate() which validates the XSAVE header contents before copying the actual states to the kernel. copyusertoxstate() was previously only called for compacted-format kernel buffers, but it works for both compacted and non-compacted forms.
Using it for the non-compacted form is slower because of multiple _copyfrom_user() operations, but that cost is less important than robust code in an already slow path.
[ Changelog polished by Dave Hansen ]
- References
Affected packages
Debian:11 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source
Debian:12 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source
Debian:13 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source