diff options
Diffstat (limited to 'system/xen/xsa/xsa248.patch')
| -rw-r--r-- | system/xen/xsa/xsa248.patch | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/system/xen/xsa/xsa248.patch b/system/xen/xsa/xsa248.patch new file mode 100644 index 0000000000..966c16e043 --- /dev/null +++ b/system/xen/xsa/xsa248.patch @@ -0,0 +1,164 @@ +From: Jan Beulich <jbeulich@suse.com> +Subject: x86/mm: don't wrongly set page ownership + +PV domains can obtain mappings of any pages owned by the correct domain, +including ones that aren't actually assigned as "normal" RAM, but used +by Xen internally. At the moment such "internal" pages marked as owned +by a guest include pages used to track logdirty bits, as well as p2m +pages and the "unpaged pagetable" for HVM guests. Since the PV memory +management and shadow code conflict in their use of struct page_info +fields, and since shadow code is being used for log-dirty handling for +PV domains, pages coming from the shadow pool must, for PV domains, not +have the domain set as their owner. + +While the change could be done conditionally for just the PV case in +shadow code, do it unconditionally (and for consistency also for HAP), +just to be on the safe side. + +There's one special case though for shadow code: The page table used for +running a HVM guest in unpaged mode is subject to get_page() (in +set_shadow_status()) and hence must have its owner set. + +This is XSA-248. + +Signed-off-by: Jan Beulich <jbeulich@suse.com> +Reviewed-by: Tim Deegan <tim@xen.org> +Reviewed-by: George Dunlap <george.dunlap@citrix.com> +--- +v2: Drop PGC_page_table related pieces. + +--- a/xen/arch/x86/mm/hap/hap.c ++++ b/xen/arch/x86/mm/hap/hap.c +@@ -286,8 +286,7 @@ static struct page_info *hap_alloc_p2m_p + { + d->arch.paging.hap.total_pages--; + d->arch.paging.hap.p2m_pages++; +- page_set_owner(pg, d); +- pg->count_info |= 1; ++ ASSERT(!page_get_owner(pg) && !(pg->count_info & PGC_count_mask)); + } + else if ( !d->arch.paging.p2m_alloc_failed ) + { +@@ -302,21 +301,23 @@ static struct page_info *hap_alloc_p2m_p + + static void hap_free_p2m_page(struct domain *d, struct page_info *pg) + { ++ struct domain *owner = page_get_owner(pg); ++ + /* This is called both from the p2m code (which never holds the + * paging lock) and the log-dirty code (which always does). */ + paging_lock_recursive(d); + +- ASSERT(page_get_owner(pg) == d); +- /* Should have just the one ref we gave it in alloc_p2m_page() */ +- if ( (pg->count_info & PGC_count_mask) != 1 ) { +- HAP_ERROR("Odd p2m page %p count c=%#lx t=%"PRtype_info"\n", +- pg, pg->count_info, pg->u.inuse.type_info); ++ /* Should still have no owner and count zero. */ ++ if ( owner || (pg->count_info & PGC_count_mask) ) ++ { ++ HAP_ERROR("d%d: Odd p2m page %"PRI_mfn" d=%d c=%lx t=%"PRtype_info"\n", ++ d->domain_id, mfn_x(page_to_mfn(pg)), ++ owner ? owner->domain_id : DOMID_INVALID, ++ pg->count_info, pg->u.inuse.type_info); + WARN(); ++ pg->count_info &= ~PGC_count_mask; ++ page_set_owner(pg, NULL); + } +- pg->count_info &= ~PGC_count_mask; +- /* Free should not decrement domain's total allocation, since +- * these pages were allocated without an owner. */ +- page_set_owner(pg, NULL); + d->arch.paging.hap.p2m_pages--; + d->arch.paging.hap.total_pages++; + hap_free(d, page_to_mfn(pg)); +--- a/xen/arch/x86/mm/shadow/common.c ++++ b/xen/arch/x86/mm/shadow/common.c +@@ -1503,32 +1503,29 @@ shadow_alloc_p2m_page(struct domain *d) + pg = mfn_to_page(shadow_alloc(d, SH_type_p2m_table, 0)); + d->arch.paging.shadow.p2m_pages++; + d->arch.paging.shadow.total_pages--; ++ ASSERT(!page_get_owner(pg) && !(pg->count_info & PGC_count_mask)); + + paging_unlock(d); + +- /* Unlike shadow pages, mark p2m pages as owned by the domain. +- * Marking the domain as the owner would normally allow the guest to +- * create mappings of these pages, but these p2m pages will never be +- * in the domain's guest-physical address space, and so that is not +- * believed to be a concern. */ +- page_set_owner(pg, d); +- pg->count_info |= 1; + return pg; + } + + static void + shadow_free_p2m_page(struct domain *d, struct page_info *pg) + { +- ASSERT(page_get_owner(pg) == d); +- /* Should have just the one ref we gave it in alloc_p2m_page() */ +- if ( (pg->count_info & PGC_count_mask) != 1 ) ++ struct domain *owner = page_get_owner(pg); ++ ++ /* Should still have no owner and count zero. */ ++ if ( owner || (pg->count_info & PGC_count_mask) ) + { +- SHADOW_ERROR("Odd p2m page count c=%#lx t=%"PRtype_info"\n", ++ SHADOW_ERROR("d%d: Odd p2m page %"PRI_mfn" d=%d c=%lx t=%"PRtype_info"\n", ++ d->domain_id, mfn_x(page_to_mfn(pg)), ++ owner ? owner->domain_id : DOMID_INVALID, + pg->count_info, pg->u.inuse.type_info); ++ pg->count_info &= ~PGC_count_mask; ++ page_set_owner(pg, NULL); + } +- pg->count_info &= ~PGC_count_mask; + pg->u.sh.type = SH_type_p2m_table; /* p2m code reuses type-info */ +- page_set_owner(pg, NULL); + + /* This is called both from the p2m code (which never holds the + * paging lock) and the log-dirty code (which always does). */ +@@ -3132,7 +3129,9 @@ int shadow_enable(struct domain *d, u32 + e = __map_domain_page(pg); + write_32bit_pse_identmap(e); + unmap_domain_page(e); ++ pg->count_info = 1; + pg->u.inuse.type_info = PGT_l2_page_table | 1 | PGT_validated; ++ page_set_owner(pg, d); + } + + paging_lock(d); +@@ -3170,7 +3169,11 @@ int shadow_enable(struct domain *d, u32 + if ( rv != 0 && !pagetable_is_null(p2m_get_pagetable(p2m)) ) + p2m_teardown(p2m); + if ( rv != 0 && pg != NULL ) ++ { ++ pg->count_info &= ~PGC_count_mask; ++ page_set_owner(pg, NULL); + shadow_free_p2m_page(d, pg); ++ } + domain_unpause(d); + return rv; + } +@@ -3279,7 +3282,22 @@ out: + + /* Must be called outside the lock */ + if ( unpaged_pagetable ) ++ { ++ if ( page_get_owner(unpaged_pagetable) == d && ++ (unpaged_pagetable->count_info & PGC_count_mask) == 1 ) ++ { ++ unpaged_pagetable->count_info &= ~PGC_count_mask; ++ page_set_owner(unpaged_pagetable, NULL); ++ } ++ /* Complain here in cases where shadow_free_p2m_page() won't. */ ++ else if ( !page_get_owner(unpaged_pagetable) && ++ !(unpaged_pagetable->count_info & PGC_count_mask) ) ++ SHADOW_ERROR("d%d: Odd unpaged pt %"PRI_mfn" c=%lx t=%"PRtype_info"\n", ++ d->domain_id, mfn_x(page_to_mfn(unpaged_pagetable)), ++ unpaged_pagetable->count_info, ++ unpaged_pagetable->u.inuse.type_info); + shadow_free_p2m_page(d, unpaged_pagetable); ++ } + } + + void shadow_final_teardown(struct domain *d) |