CVE-2021-3491

NameCVE-2021-3491
DescriptionThe io_uring subsystem in the Linux kernel allowed the MAX_RW_COUNT limit to be bypassed in the PROVIDE_BUFFERS operation, which led to negative values being usedin mem_rw when reading /proc/<PID>/mem. This could be used to create a heap overflow leading to arbitrary code execution in the kernel. It was addressed via commit d1f82808877b ("io_uring: truncate lengths larger than MAX_RW_COUNT on provide buffers") (v5.13-rc1) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. It was introduced in ddf0322db79c ("io_uring: add IORING_OP_PROVIDE_BUFFERS") (v5.7-rc1).
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severityhigh

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)stretch4.9.228-1fixed
stretch (security)4.9.272-2fixed
buster4.19.194-1fixed
buster (security)4.19.194-3fixed
bullseye (security)5.10.46-5fixed
bookworm, bullseye5.10.46-4fixed
sid5.14.6-2fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcestretch(not affected)
linuxsourcebuster(not affected)
linuxsource(unstable)5.10.38-1

Notes

[buster] - linux <not-affected> (Vulnerable code introduced later)
[stretch] - linux <not-affected> (Vulnerable code introduced later)
https://www.openwall.com/lists/oss-security/2021/05/11/13
https://git.kernel.org/linus/d1f82808877bb10d3deee7cf3374a4eb3fb582db

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