CVE-2021-28715

NameCVE-2021-28715
DescriptionGuest can force Linux netback driver to hog large amounts of kernel memory T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Incoming data packets for a guest in the Linux kernel's netback driver are buffered until the guest is ready to process them. There are some measures taken for avoiding to pile up too much data, but those can be bypassed by the guest: There is a timeout how long the client side of an interface can stop consuming new packets before it is assumed to have stalled, but this timeout is rather long (60 seconds by default). Using a UDP connection on a fast interface can easily accumulate gigabytes of data in that time. (CVE-2021-28715) The timeout could even never trigger if the guest manages to have only one free slot in its RX queue ring page and the next package would require more than one free slot, which may be the case when using GSO, XDP, or software hashing. (CVE-2021-28714)
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-2940-1, DLA-2941-1, DSA-5050-1, DSA-5096-1, ELA-577-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)jessie, jessie (lts)3.16.84-1vulnerable
stretch (security)4.9.320-2fixed
stretch (lts), stretch4.9.320-3fixed
buster (security), buster, buster (lts)4.19.316-1fixed
bullseye5.10.223-1fixed
bullseye (security)5.10.226-1fixed
bookworm6.1.115-1fixed
bookworm (security)6.1.112-1fixed
trixie6.11.7-1fixed
sid6.11.9-1fixed
linux-4.19 (PTS)stretch (security)4.19.232-1~deb9u1fixed
stretch (lts), stretch4.19.316-1~deb9u1fixed
linux-4.9 (PTS)jessie, jessie (lts)4.9.303-1~deb8u3fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcejessie(unfixed)end-of-life
linuxsourcestretch4.9.303-1DLA-2940-1
linuxsourcebuster4.19.232-1DSA-5096-1
linuxsourcebullseye5.10.92-1DSA-5050-1
linuxsource(unstable)5.15.15-1
linux-4.19sourcestretch4.19.232-1~deb9u1DLA-2941-1
linux-4.9sourcejessie4.9.303-1~deb8u1ELA-577-1

Notes

https://xenbits.xen.org/xsa/advisory-392.html

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