diff options
Diffstat (limited to 'main/xen/xsa389-4.13.patch')
| -rw-r--r-- | main/xen/xsa389-4.13.patch | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/main/xen/xsa389-4.13.patch b/main/xen/xsa389-4.13.patch new file mode 100644 index 00000000000..10a8a9b9ed8 --- /dev/null +++ b/main/xen/xsa389-4.13.patch @@ -0,0 +1,180 @@ +From: Jan Beulich <jbeulich@suse.com> +Subject: x86/P2M: deal with partial success of p2m_set_entry() + +M2P and PoD stats need to remain in sync with P2M; if an update succeeds +only partially, respective adjustments need to be made. If updates get +made before the call, they may also need undoing upon complete failure +(i.e. including the single-page case). + +Log-dirty state would better also be kept in sync. + +Note that the change to set_typed_p2m_entry() may not be strictly +necessary (due to the order restriction enforced near the top of the +function), but is being kept here to be on the safe side. + +This is CVE-2021-28705 and CVE-2021-28709 / XSA-389. + +Signed-off-by: Jan Beulich <jbeulich@suse.com> +Reviewed-by: Roger Pau Monné <roger.pau@citrix.com> + +--- a/xen/arch/x86/mm/p2m.c ++++ b/xen/arch/x86/mm/p2m.c +@@ -781,6 +781,7 @@ p2m_remove_page(struct p2m_domain *p2m, + gfn_t gfn = _gfn(gfn_l); + p2m_type_t t; + p2m_access_t a; ++ int rc; + + /* IOMMU for PV guests is handled in get_page_type() and put_page(). */ + if ( !paging_mode_translate(p2m->domain) ) +@@ -812,8 +813,27 @@ p2m_remove_page(struct p2m_domain *p2m, + set_gpfn_from_mfn(mfn+i, INVALID_M2P_ENTRY); + } + } +- return p2m_set_entry(p2m, gfn, INVALID_MFN, page_order, p2m_invalid, +- p2m->default_access); ++ rc = p2m_set_entry(p2m, gfn, INVALID_MFN, page_order, p2m_invalid, ++ p2m->default_access); ++ if ( likely(!rc) || !mfn_valid(_mfn(mfn)) ) ++ return rc; ++ ++ /* ++ * The operation may have partially succeeded. For the failed part we need ++ * to undo the M2P update and, out of precaution, mark the pages dirty ++ * again. ++ */ ++ for ( i = 0; i < (1UL << page_order); ++i ) ++ { ++ p2m->get_entry(p2m, gfn_add(gfn, i), &t, &a, 0, NULL, NULL); ++ if ( !p2m_is_hole(t) && !p2m_is_special(t) && !p2m_is_shared(t) ) ++ { ++ set_gpfn_from_mfn(mfn + i, gfn_l + i); ++ paging_mark_pfn_dirty(p2m->domain, _pfn(gfn_l + i)); ++ } ++ } ++ ++ return rc; + } + + int +@@ -1002,13 +1022,8 @@ guest_physmap_add_entry(struct domain *d + + /* Now, actually do the two-way mapping */ + rc = p2m_set_entry(p2m, gfn, mfn, page_order, t, p2m->default_access); +- if ( rc == 0 ) ++ if ( likely(!rc) ) + { +- pod_lock(p2m); +- p2m->pod.entry_count -= pod_count; +- BUG_ON(p2m->pod.entry_count < 0); +- pod_unlock(p2m); +- + if ( !p2m_is_grant(t) ) + { + for ( i = 0; i < (1UL << page_order); i++ ) +@@ -1016,6 +1031,42 @@ guest_physmap_add_entry(struct domain *d + gfn_x(gfn_add(gfn, i))); + } + } ++ else ++ { ++ /* ++ * The operation may have partially succeeded. For the successful part ++ * we need to update M2P and dirty state, while for the failed part we ++ * may need to adjust PoD stats as well as undo the earlier M2P update. ++ */ ++ for ( i = 0; i < (1UL << page_order); ++i ) ++ { ++ omfn = p2m->get_entry(p2m, gfn_add(gfn, i), &ot, &a, 0, NULL, NULL); ++ if ( p2m_is_pod(ot) ) ++ { ++ BUG_ON(!pod_count); ++ --pod_count; ++ } ++ else if ( mfn_eq(omfn, mfn_add(mfn, i)) && ot == t && ++ a == p2m->default_access && !p2m_is_grant(t) ) ++ { ++ set_gpfn_from_mfn(mfn_x(omfn), gfn_x(gfn) + i); ++ paging_mark_pfn_dirty(d, _pfn(gfn_x(gfn) + i)); ++ } ++ else if ( p2m_is_ram(ot) && !p2m_is_paged(ot) ) ++ { ++ ASSERT(mfn_valid(omfn)); ++ set_gpfn_from_mfn(mfn_x(omfn), gfn_x(gfn) + i); ++ } ++ } ++ } ++ ++ if ( pod_count ) ++ { ++ pod_lock(p2m); ++ p2m->pod.entry_count -= pod_count; ++ BUG_ON(p2m->pod.entry_count < 0); ++ pod_unlock(p2m); ++ } + + out: + p2m_unlock(p2m); +@@ -1307,6 +1358,49 @@ static int set_typed_p2m_entry(struct do + return 0; + } + } ++ ++ P2M_DEBUG("set %d %lx %lx\n", gfn_p2mt, gfn_l, mfn_x(mfn)); ++ rc = p2m_set_entry(p2m, gfn, mfn, order, gfn_p2mt, access); ++ if ( unlikely(rc) ) ++ { ++ gdprintk(XENLOG_ERR, "p2m_set_entry: %#lx:%u -> %d (0x%"PRI_mfn")\n", ++ gfn_l, order, rc, mfn_x(mfn)); ++ ++ /* ++ * The operation may have partially succeeded. For the successful part ++ * we need to update PoD stats, M2P, and dirty state. ++ */ ++ if ( order != PAGE_ORDER_4K ) ++ { ++ unsigned long i; ++ ++ for ( i = 0; i < (1UL << order); ++i ) ++ { ++ p2m_type_t t; ++ mfn_t cmfn = p2m->get_entry(p2m, gfn_add(gfn, i), &t, &a, 0, ++ NULL, NULL); ++ ++ if ( !mfn_eq(cmfn, mfn_add(mfn, i)) || t != gfn_p2mt || ++ a != access ) ++ continue; ++ ++ if ( p2m_is_ram(ot) ) ++ { ++ ASSERT(mfn_valid(mfn_add(omfn, i))); ++ set_gpfn_from_mfn(mfn_x(omfn) + i, INVALID_M2P_ENTRY); ++ } ++#ifdef CONFIG_HVM ++ else if ( p2m_is_pod(ot) ) ++ { ++ pod_lock(p2m); ++ BUG_ON(!p2m->pod.entry_count); ++ --p2m->pod.entry_count; ++ pod_unlock(p2m); ++ } ++#endif ++ } ++ } ++ } + else if ( p2m_is_ram(ot) ) + { + unsigned long i; +@@ -1317,12 +1411,6 @@ static int set_typed_p2m_entry(struct do + set_gpfn_from_mfn(mfn_x(omfn) + i, INVALID_M2P_ENTRY); + } + } +- +- P2M_DEBUG("set %d %lx %lx\n", gfn_p2mt, gfn_l, mfn_x(mfn)); +- rc = p2m_set_entry(p2m, gfn, mfn, order, gfn_p2mt, access); +- if ( rc ) +- gdprintk(XENLOG_ERR, "p2m_set_entry: %#lx:%u -> %d (0x%"PRI_mfn")\n", +- gfn_l, order, rc, mfn_x(mfn)); + #ifdef CONFIG_HVM + else if ( p2m_is_pod(ot) ) + { |