diff options
| author | Ian Jackson <Ian.Jackson@eu.citrix.com> | 2012-11-14 11:42:45 +0000 |
|---|---|---|
| committer | Ian Jackson <Ian.Jackson@eu.citrix.com> | 2012-11-14 11:42:45 +0000 |
| commit | 33df3b4a744312c01a8fa9929f06d62a81f50c28 (patch) | |
| tree | 058ef971040ca571697c28a1d665d41a08c50952 | |
| parent | c870348ef5895bca245cf4fc9c1c3f452ccf9fa1 (diff) | |
| download | xen-33df3b4a744312c01a8fa9929f06d62a81f50c28.tar.gz xen-33df3b4a744312c01a8fa9929f06d62a81f50c28.tar.bz2 xen-33df3b4a744312c01a8fa9929f06d62a81f50c28.zip | |
xen/mm/shadow: check toplevel pagetables are present before unhooking them.
If the guest has not fully populated its top-level PAE entries when it calls
HVMOP_pagetable_dying, the shadow code could try to unhook entries from
MFN 0. Add a check to avoid that case.
This issue was introduced by c/s 21239:b9d2db109cf5.
This is a security problem, XSA-23 / CVE-2012-4538.
Signed-off-by: Tim Deegan <tim@xen.org>
Tested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
xen-unstable changeset: 26150:c7a01b6450e4
Backport-requested-by: security@xen.org
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
| -rw-r--r-- | xen/arch/x86/mm/shadow/multi.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c index 2fae26b6f4..ca4a24170e 100644 --- a/xen/arch/x86/mm/shadow/multi.c +++ b/xen/arch/x86/mm/shadow/multi.c @@ -4734,8 +4734,12 @@ static void sh_pagetable_dying(struct vcpu *v, paddr_t gpa) unsigned long gfn; mfn_t smfn, gmfn; - if ( fast_path ) - smfn = _mfn(pagetable_get_pfn(v->arch.shadow_table[i])); + if ( fast_path ) { + if ( pagetable_is_null(v->arch.shadow_table[i]) ) + smfn = _mfn(INVALID_MFN); + else + smfn = _mfn(pagetable_get_pfn(v->arch.shadow_table[i])); + } else { /* retrieving the l2s */ |