OracleVM 3.3 : xen (OVMSA-2016-0103)
Medium Nessus Plugin ID 93396
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: Andrew Cooper Subject: x86/shadow: Avoid overflowing sh_ctxt->seg_reg hvm_get_seg_reg does not perform a range check on its input segment, calls hvm_get_segment_register and writes straight into sh_ctxt->seg_reg. x86_seg_none is outside the bounds of sh_ctxt->seg_reg, and will hit a BUG in [vmx,svm]_get_segment_register. HVM guests running with shadow paging can end up performing a virtual to linear translation with x86_seg_none. This is used for addresses which are already linear. However, none of this is a legitimate pagetable update, so fail the emulation in such a case. This is XSA-187 (CVE-2016-7094)
- x86/32on64: don't allow recursive page tables from L3 L3 entries are special in PAE mode, and hence can't reasonably be used for setting up recursive (and hence linear) page table mappings. Since abuse is possible when the guest in fact gets run on 4-level page tables, this needs to be excluded explicitly. This is XSA-185.
SolutionUpdate the affected xen / xen-tools packages.