CVE-2021-3527

Name	CVE-2021-3527
Description	A flaw was found in the USB redirector device (usb-redir) of QEMU. Small USB packets are combined into a single, large transfer request, to reduce the overhead and improve performance. The combined size of the bulk transfer is used to dynamically allocate a variable length array (VLA) on the stack without proper validation. Since the total size is not bounded, a malicious guest could use this flaw to influence the array length and cause the QEMU process to perform an excessive allocation on the stack, resulting in a denial of service.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DLA-2753-1, DLA-3099-1
Debian Bugs	988157

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
qemu (PTS)	bullseye	1:5.2+dfsg-11+deb11u3	fixed
	bullseye (security)	1:5.2+dfsg-11+deb11u2	fixed
	bookworm	1:7.2+dfsg-7+deb12u7	fixed
	trixie	1:9.0.2+ds-2	fixed
	sid	1:9.1.0+ds-3	fixed

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

Package	Type	Release	Fixed Version	Origin	Debian Bugs
qemu	source	stretch	1:2.8+dfsg-6+deb9u15	DLA-2753-1
qemu	source	buster	1:3.1+dfsg-8+deb10u9	DLA-3099-1
qemu	source	(unstable)	1:5.2+dfsg-11		988157

Notes

Initial patchset: https://lists.nongnu.org/archive/html/qemu-devel/2021-05/msg00564.html
Revisited: https://lists.nongnu.org/archive/html/qemu-devel/2021-05/msg01372.html
https://lists.nongnu.org/archive/html/qemu-devel/2021-05/msg01373.html
https://gitlab.com/qemu-project/qemu/-/commit/7ec54f9eb62b5d177e30eb8b1cad795a5f8d8986
https://gitlab.com/qemu-project/qemu/-/commit/05a40b172e4d691371534828078be47e7fff524c