CVE-2018-8897

NameCVE-2018-8897
DescriptionA statement in the System Programming Guide of the Intel 64 and IA-32 Architectures Software Developer's Manual (SDM) was mishandled in the development of some or all operating-system kernels, resulting in unexpected behavior for #DB exceptions that are deferred by MOV SS or POP SS, as demonstrated by (for example) privilege escalation in Windows, macOS, some Xen configurations, or FreeBSD, or a Linux kernel crash. The MOV to SS and POP SS instructions inhibit interrupts (including NMIs), data breakpoints, and single step trap exceptions until the instruction boundary following the next instruction (SDM Vol. 3A; section 6.8.3). (The inhibited data breakpoints are those on memory accessed by the MOV to SS or POP to SS instruction itself.) Note that debug exceptions are not inhibited by the interrupt enable (EFLAGS.IF) system flag (SDM Vol. 3A; section 2.3). If the instruction following the MOV to SS or POP to SS instruction is an instruction like SYSCALL, SYSENTER, INT 3, etc. that transfers control to the operating system at CPL < 3, the debug exception is delivered after the transfer to CPL < 3 is complete. OS kernels may not expect this order of events and may therefore experience unexpected behavior when it occurs.
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)
ReferencesDSA-4196-1, DSA-4201-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)wheezy3.2.78-1vulnerable
wheezy (security)3.2.101-1vulnerable
jessie3.16.51-2vulnerable
jessie (security)3.16.56-1+deb8u1fixed
stretch4.9.82-1+deb9u3vulnerable
stretch (security)4.9.88-1+deb9u1fixed
buster, sid4.16.5-1fixed
xen (PTS)wheezy4.1.4-3+deb7u9vulnerable
wheezy (security)4.1.6.lts1-13vulnerable
jessie (security), jessie4.4.1-9+deb8u10vulnerable
buster, sid, stretch4.8.3+comet2+shim4.10.0+comet3-1+deb9u5vulnerable
stretch (security)4.8.3+xsa262+shim4.10.0+comet3-1+deb9u6fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsource(unstable)4.15.17-1
linuxsourcejessie3.16.56-1+deb8u1DSA-4196-1
linuxsourcestretch4.9.88-1+deb9u1DSA-4196-1
xensource(unstable)(unfixed)
xensourcestretch4.8.3+xsa262+shim4.10.0+comet3-1+deb9u6DSA-4201-1

Notes

Fixed by: https://git.kernel.org/linus/d8ba61ba58c88d5207c1ba2f7d9a2280e7d03be9 (4.16-rc7)
https://xenbits.xen.org/xsa/advisory-260.html
http://www.openwall.com/lists/oss-security/2018/05/08/4

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