OracleVM 3.3 : xen (OVMSA-2017-0148)
High Nessus Plugin ID 102906
SynopsisThe remote OracleVM host is missing one or more security updates.
DescriptionThe remote OracleVM system is missing necessary patches to address critical security updates :
- From: Jan Beulich Subject: gnttab: correct pin status fixup for copy Regardless of copy operations only setting GNTPIN_hst*, GNTPIN_dev* also need to be taken into account when deciding whether to clear
_GTF_[read,writ]ing. At least for consistency with code elsewhere the read part better doesn't use any mask at all. This is XSA-230. (CVE-2017-12855)
- From: Andrew Cooper Subject: grant_table: Default to v1, and disallow transitive grants The reference counting and locking discipline for transitive grants is broken.
Their use is therefore declared out of security support.
This is XSA-226. Transitive grants are expected to be unconditionally available with grant table v2. Hiding transitive grants alone is an ABI breakage for the guest. Modern versions of Linux and the Windows PV drivers use grant table v1, but older versions did use v2. In principle, disabling gnttab v2 entirely is the safer way to cause guests to avoid using transitive grants. However, some older guests which defaulted to using gnttab v2 don't tolerate falling back from v2 to v1 over migrate. This patch introduces a new command line option to control grant table behaviour. One suboption allows a choice of the maximum grant table version Xen will allow the guest to use, and defaults to v2. A different suboption independently controls whether transitive grants can be used. The default case is:
gnttab=max_ver:2 To disable gnttab v2 entirely, use:
gnttab=max_ver:1 To allow gnttab v2 and transitive grants, use: gnttab=max_ver:2,transitive
Conflict: docs/misc/xen-command-line.markdown (CVE-2017-12135)
- Revert wrong fix for xsa226 [bug 26567225]
- From 3aab881c7331cf93ffd8d2f2dd9adfd18ed4fc99 Mon Sep 17 00:00:00 2001 From: Andrew Cooper Date: Tue, 20 Jun 2017 19:18:54 +0100 Subject: [PATCH] x86/grant: Disallow misaligned PTEs Pagetable entries must be aligned to function correctly. Disallow attempts from the guest to have a grant PTE created at a misaligned address, which would result in corruption of the L1 table with largely-guest-controlled values. This is XSA-227 (CVE-2017-12137)
- Prerequisite patch for xsa227-4.5.patch There is no macro ASSERT_UNREACHABLE before OVM3.4 which is needed by xsa227-4.5.patch This chunk is picked from upstream commit cacdb0faaa121ac8f792d5bd34cc6bc7c72d21da (CVE-2017-12137)
- From: Jan Beulich Subject: gnttab: don't use possibly unbounded tail calls There is no guarantee that the compiler would actually translate them to branches instead of calls, so only ones with a known recursion limit are okay :
- __release_grant_for_copy can call itself only once, as
__acquire_grant_for_copy won't permit use of multi-level transitive grants,
- __acquire_grant_for_copy is fine to call itself with the last argument false, as that prevents further recursion,
- __acquire_grant_for_copy must not call itself to recover from an observed change to the active entry's pin count This is XSA-226. (CVE-2017-12135)
- From 69549b08eb9bd3a525c07a97d952673a3d02c76a Mon Sep 17 00:00:00 2001 From: Annie Li Date: Fri, 7 Jul 2017 14:36:08 -0400 Subject: [PATCH] xen: increase default max grant frames and max maptrack frames Commit 9dfba034e increase default max grant frames to 128 which is still not enough when the guest has more cpus and vbd/vif devices, so set it to 256. Also the default max maptrack frames needs to be increased accordingly.
SolutionUpdate the affected xen / xen-tools packages.