diff options
| author | Ian Jackson <Ian.Jackson@eu.citrix.com> | 2012-11-14 11:43:29 +0000 |
|---|---|---|
| committer | Ian Jackson <Ian.Jackson@eu.citrix.com> | 2012-11-14 11:43:29 +0000 |
| commit | 1d435032de14b9dec808102940309047903f7ed0 (patch) | |
| tree | afd29e8047bcb2ee9b01c049b241e21dafece422 | |
| parent | 9070a6ef041756341286e88e7fad7de3e01c66f9 (diff) | |
| download | xen-1d435032de14b9dec808102940309047903f7ed0.tar.gz xen-1d435032de14b9dec808102940309047903f7ed0.tar.bz2 xen-1d435032de14b9dec808102940309047903f7ed0.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>
| -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 d510e7f707..91879cfc9e 100644 --- a/xen/arch/x86/mm/shadow/multi.c +++ b/xen/arch/x86/mm/shadow/multi.c @@ -4737,8 +4737,12 @@ static void sh_pagetable_dying(struct vcpu *v, paddr_t gpa) } for ( i = 0; i < 4; i++ ) { - 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 */ |