CVE-2021-4095

NameCVE-2021-4095
DescriptionA NULL pointer dereference was found in the Linux kernel's KVM when dirty ring logging is enabled without an active vCPU context. An unprivileged local attacker on the host may use this flaw to cause a kernel oops condition and thus a denial of service by issuing a KVM_XEN_HVM_SET_ATTR ioctl. This flaw affects Linux kernel versions prior to 5.17-rc1.
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)

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
linuxsourcestretch(not affected)
linuxsourcebuster(not affected)
linuxsourcebullseye(not affected)
linuxsource(unstable)5.17.3-1

Notes

[bullseye] - linux <not-affected> (Vulnerable code introduced later)
[buster] - linux <not-affected> (Vulnerable code introduced later)
[stretch] - linux <not-affected> (Vulnerable code introduced later)
https://lore.kernel.org/kvm/CAFcO6XOmoS7EacN_n6v4Txk7xL7iqRa2gABg3F7E3Naf5uG94g@mail.gmail.com/
https://patchwork.kernel.org/project/kvm/patch/20211121125451.9489-12-dwmw2@infradead.org/
https://bugzilla.redhat.com/show_bug.cgi?id=2031194

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