CVE-2020-29569

NameCVE-2020-29569
DescriptionAn issue was discovered in the Linux kernel through 5.10.1, as used with Xen through 4.14.x. The Linux kernel PV block backend expects the kernel thread handler to reset ring->xenblkd to NULL when stopped. However, the handler may not have time to run if the frontend quickly toggles between the states connect and disconnect. As a consequence, the block backend may re-use a pointer after it was freed. A misbehaving guest can trigger a dom0 crash by continuously connecting / disconnecting a block frontend. Privilege escalation and information leaks cannot be ruled out. This only affects systems with a Linux blkback.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub advisories/code/issues, web search, more)
ReferencesDLA-2557-1, DLA-2586-1, DSA-4843-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)buster4.19.249-2fixed
buster (security)4.19.260-1fixed
bullseye5.10.140-1fixed
bullseye (security)5.10.149-2fixed
bookworm6.0.10-1fixed
sid6.0.10-2fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcestretch4.9.258-1DLA-2586-1
linuxsourcebuster4.19.171-2DSA-4843-1
linuxsource(unstable)5.9.15-1
linux-4.19sourcestretch4.19.171-2~deb9u1DLA-2557-1

Notes

https://xenbits.xen.org/xsa/advisory-350.html

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