gnttab/ARM: don't corrupt shared GFN array

... by writing status GFNs to it. Introduce a second array instead.
Also implement gnttab_status_gmfn() properly now that the information is
suitably being tracked.

While touching it anyway, remove a misguided (but luckily benign) upper
bound check from gnttab_shared_gmfn(): We should never access beyond the
bounds of that array.

This is part of XSA-255.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 9d2f8f9c65d4da35437f50ed9e812a2c5ab313e2
master date: 2018-02-27 14:04:44 +0100

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 1365b4ad4be546c03986a7dabdbab0dca473d624..122e26144c59e3b19cec59af7ca8908d04298b4e 100644 (file)
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -438,19 +438,37 @@ void startup_cpu_idle_loop(void)
 struct domain *alloc_domain_struct(void)
 {
     struct domain *d;
+    unsigned int i, max_status_frames;
+
     BUILD_BUG_ON(sizeof(*d) > PAGE_SIZE);
     d = alloc_xenheap_pages(0, 0);
     if ( d == NULL )
         return NULL;
 
     clear_page(d);
-    d->arch.grant_table_gpfn = xzalloc_array(xen_pfn_t, max_grant_frames);
+
+    d->arch.grant_shared_gfn = xmalloc_array(gfn_t, max_grant_frames);
+    max_status_frames = grant_to_status_frames(max_grant_frames);
+    d->arch.grant_status_gfn = xmalloc_array(gfn_t, max_status_frames);
+    if ( !d->arch.grant_shared_gfn || !d->arch.grant_status_gfn )
+    {
+        free_domain_struct(d);
+        return NULL;
+    }
+
+    for ( i = 0; i < max_grant_frames; ++i )
+        d->arch.grant_shared_gfn[i] = _gfn(INVALID_GFN);
+
+    for ( i = 0; i < max_status_frames; ++i )
+        d->arch.grant_status_gfn[i] = _gfn(INVALID_GFN);
+
     return d;
 }
 
 void free_domain_struct(struct domain *d)
 {
-    xfree(d->arch.grant_table_gpfn);
+    xfree(d->arch.grant_shared_gfn);
+    xfree(d->arch.grant_status_gfn);
     free_xenheap_page(d);
 }
 

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 0a8269851f3ee6bad1f7cdba8b339c47e85cd8f2..9928c828565fbf7f88abc86d3fb142530fdd85be 100644 (file)
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -1065,6 +1065,7 @@ int xenmem_add_to_physmap_one(
     int rc;
     p2m_type_t t;
     struct page_info *page = NULL;
+    bool_t status = 0;
 
     switch ( space )
     {
@@ -1082,6 +1083,7 @@ int xenmem_add_to_physmap_one(
                 mfn = virt_to_mfn(d->grant_table->status[idx]);
             else
                 mfn = INVALID_MFN;
+            status = 1;
         }
         else
         {
@@ -1097,7 +1099,10 @@ int xenmem_add_to_physmap_one(
         
         if ( mfn != INVALID_MFN )
         {
-            d->arch.grant_table_gpfn[idx] = gpfn;
+            if ( status )
+                d->arch.grant_status_gfn[idx] = _gfn(gpfn);
+            else
+                d->arch.grant_shared_gfn[idx] = _gfn(gpfn);
 
             t = p2m_ram_rw;
         }

diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
index 370cdeb610338b26a4b909dbc68b6c2ed086e45b..cb1ffecdf90c82be297de6f319747186a09a4713 100644 (file)
--- a/xen/include/asm-arm/domain.h
+++ b/xen/include/asm-arm/domain.h
@@ -51,7 +51,8 @@ struct arch_domain
     uint64_t vttbr;
 
     struct hvm_domain hvm_domain;
-    xen_pfn_t *grant_table_gpfn;
+    gfn_t *grant_shared_gfn;
+    gfn_t *grant_status_gfn;
 
     struct vmmio vmmio;
 

diff --git a/xen/include/asm-arm/grant_table.h b/xen/include/asm-arm/grant_table.h
index d76c7c774a9b6d6eedb3f0bb07aee70982f9bec0..a51cc6579ca3d19cf4d52c78c05f4f8b287de41b 100644 (file)
--- a/xen/include/asm-arm/grant_table.h
+++ b/xen/include/asm-arm/grant_table.h
@@ -14,7 +14,6 @@ int replace_grant_host_mapping(unsigned long gpaddr, unsigned long mfn,
         unsigned long new_gpaddr, unsigned int flags);
 void gnttab_mark_dirty(struct domain *d, unsigned long l);
 #define gnttab_create_status_page(d, t, i) do {} while (0)
-#define gnttab_status_gmfn(d, t, i) (0)
 #define gnttab_release_host_mappings(domain) 1
 static inline int replace_grant_supported(void)
 {
@@ -29,8 +28,12 @@ static inline int replace_grant_supported(void)
     } while ( 0 )
 
 #define gnttab_shared_gmfn(d, t, i)                                      \
-    ( ((i >= nr_grant_frames(d->grant_table)) &&                         \
-     (i < max_grant_frames)) ? 0 : (d->arch.grant_table_gpfn[i]))
+    gfn_x(((i) >= nr_grant_frames(t)) ? _gfn(INVALID_GFN)                \
+                                      : (d)->arch.grant_shared_gfn[i])
+
+#define gnttab_status_gmfn(d, t, i)                                      \
+    gfn_x(((i) >= nr_status_frames(t)) ? _gfn(INVALID_GFN)               \
+                                       : (d)->arch.grant_status_gfn[i])
 
 #define gnttab_need_iommu_mapping(d)                    \
     (is_domain_direct_mapped(d) && need_iommu(d))