From: Jan Beulich <jbeulich@suse.com>
Subject: guest_physmap_remove_page() needs its return value checked
Callers, namely such subsequently freeing the page, must not blindly
assume success - the function may namely fail when needing to shatter a
super page, but there not being memory available for the then needed
intermediate page table.
As it happens, guest_remove_page() callers now also all check the
return value.
Furthermore a missed put_gfn() on an error path in gnttab_transfer() is
also being taken care of.
This is part of XSA-222.
Reported-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -1340,13 +1340,14 @@ int replace_grant_host_mapping(unsigned
{
gfn_t gfn = _gfn(addr >> PAGE_SHIFT);
struct domain *d = current->domain;
+ int rc;
if ( new_addr != 0 || (flags & GNTMAP_contains_pte) )
return GNTST_general_error;
- guest_physmap_remove_page(d, gfn, _mfn(mfn), 0);
+ rc = guest_physmap_remove_page(d, gfn, _mfn(mfn), 0);
- return GNTST_okay;
+ return rc ? GNTST_general_error : GNTST_okay;
}
int is_iomem_page(unsigned long mfn)
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -1211,11 +1211,10 @@ int guest_physmap_add_entry(struct domai
return p2m_insert_mapping(d, gfn, (1 << page_order), mfn, t);
}
-void guest_physmap_remove_page(struct domain *d,
- gfn_t gfn,
- mfn_t mfn, unsigned int page_order)
+int guest_physmap_remove_page(struct domain *d, gfn_t gfn, mfn_t mfn,
+ unsigned int page_order)
{
- p2m_remove_mapping(d, gfn, (1 << page_order), mfn);
+ return p2m_remove_mapping(d, gfn, (1 << page_order), mfn);
}
static int p2m_alloc_table(struct domain *d)
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -808,7 +808,15 @@ int arch_domain_soft_reset(struct domain
ret = -ENOMEM;
goto exit_put_gfn;
}
- guest_physmap_remove_page(d, _gfn(gfn), _mfn(mfn), PAGE_ORDER_4K);
+
+ ret = guest_physmap_remove_page(d, _gfn(gfn), _mfn(mfn), PAGE_ORDER_4K);
+ if ( ret )
+ {
+ printk(XENLOG_G_ERR "Failed to remove Dom%d's shared_info frame %lx\n",
+ d->domain_id, gfn);
+ free_domheap_page(new_page);
+ goto exit_put_gfn;
+ }
ret = guest_physmap_add_page(d, _gfn(gfn), _mfn(page_to_mfn(new_page)),
PAGE_ORDER_4K);
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -427,7 +427,9 @@ static __init void pvh_add_mem_mapping(s
if ( !iomem_access_permitted(d, mfn + i, mfn + i) )
{
omfn = get_gfn_query_unlocked(d, gfn + i, &t);
- guest_physmap_remove_page(d, _gfn(gfn + i), omfn, PAGE_ORDER_4K);
+ if ( guest_physmap_remove_page(d, _gfn(gfn + i), omfn,
+ PAGE_ORDER_4K) )
+ /* nothing, best effort only */;
continue;
}
--- a/xen/arch/x86/hvm/ioreq.c
+++ b/xen/arch/x86/hvm/ioreq.c
@@ -267,8 +267,9 @@ bool_t is_ioreq_server_page(struct domai
static void hvm_remove_ioreq_gmfn(
struct domain *d, struct hvm_ioreq_page *iorp)
{
- guest_physmap_remove_page(d, _gfn(iorp->gmfn),
- _mfn(page_to_mfn(iorp->page)), 0);
+ if ( guest_physmap_remove_page(d, _gfn(iorp->gmfn),
+ _mfn(page_to_mfn(iorp->page)), 0) )
+ domain_crash(d);
clear_page(iorp->va);
}
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4276,7 +4276,11 @@ static int replace_grant_p2m_mapping(
type, mfn_x(old_mfn), frame);
return GNTST_general_error;
}
- guest_physmap_remove_page(d, _gfn(gfn), _mfn(frame), PAGE_ORDER_4K);
+ if ( guest_physmap_remove_page(d, _gfn(gfn), _mfn(frame), PAGE_ORDER_4K) )
+ {
+ put_gfn(d, gfn);
+ return GNTST_general_error;
+ }
put_gfn(d, gfn);
return GNTST_okay;
@@ -4798,7 +4802,7 @@ int xenmem_add_to_physmap_one(
struct page_info *page = NULL;
unsigned long gfn = 0; /* gcc ... */
unsigned long prev_mfn, mfn = 0, old_gpfn;
- int rc;
+ int rc = 0;
p2m_type_t p2mt;
switch ( space )
@@ -4872,25 +4876,30 @@ int xenmem_add_to_physmap_one(
{
if ( is_xen_heap_mfn(prev_mfn) )
/* Xen heap frames are simply unhooked from this phys slot. */
- guest_physmap_remove_page(d, gpfn, _mfn(prev_mfn), PAGE_ORDER_4K);
+ rc = guest_physmap_remove_page(d, gpfn, _mfn(prev_mfn), PAGE_ORDER_4K);
else
/* Normal domain memory is freed, to avoid leaking memory. */
- guest_remove_page(d, gfn_x(gpfn));
+ rc = guest_remove_page(d, gfn_x(gpfn));
}
/* In the XENMAPSPACE_gmfn case we still hold a ref on the old page. */
put_gfn(d, gfn_x(gpfn));
+ if ( rc )
+ goto put_both;
+
/* Unmap from old location, if any. */
old_gpfn = get_gpfn_from_mfn(mfn);
ASSERT( old_gpfn != SHARED_M2P_ENTRY );
if ( space == XENMAPSPACE_gmfn || space == XENMAPSPACE_gmfn_range )
ASSERT( old_gpfn == gfn );
if ( old_gpfn != INVALID_M2P_ENTRY )
- guest_physmap_remove_page(d, _gfn(old_gpfn), _mfn(mfn), PAGE_ORDER_4K);
+ rc = guest_physmap_remove_page(d, _gfn(old_gpfn), _mfn(mfn), PAGE_ORDER_4K);
/* Map at new location. */
- rc = guest_physmap_add_page(d, gpfn, _mfn(mfn), PAGE_ORDER_4K);
+ if ( !rc )
+ rc = guest_physmap_add_page(d, gpfn, _mfn(mfn), PAGE_ORDER_4K);
+ put_both:
/* In the XENMAPSPACE_gmfn, we took a ref of the gfn at the top */
if ( space == XENMAPSPACE_gmfn || space == XENMAPSPACE_gmfn_range )
put_gfn(d, gfn);
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -2925,10 +2925,12 @@ int p2m_add_foreign(struct domain *tdom,
{
if ( is_xen_heap_mfn(mfn_x(prev_mfn)) )
/* Xen heap frames are simply unhooked from this phys slot */
- guest_physmap_remove_page(tdom, _gfn(gpfn), prev_mfn, 0);
+ rc = guest_physmap_remove_page(tdom, _gfn(gpfn), prev_mfn, 0);
else
/* Normal domain memory is freed, to avoid leaking memory. */
- guest_remove_page(tdom, gpfn);
+ rc = guest_remove_page(tdom, gpfn);
+ if ( rc )
+ goto put_both;
}
/*
* Create the new mapping. Can't use guest_physmap_add_page() because it
@@ -2941,6 +2943,7 @@ int p2m_add_foreign(struct domain *tdom,
"gpfn:%lx mfn:%lx fgfn:%lx td:%d fd:%d\n",
gpfn, mfn_x(mfn), fgfn, tdom->domain_id, fdom->domain_id);
+ put_both:
put_page(page);
/*
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -1768,6 +1768,7 @@ gnttab_transfer(
for ( i = 0; i < count; i++ )
{
bool_t okay;
+ int rc;
if (i && hypercall_preempt_check())
return i;
@@ -1818,27 +1819,33 @@ gnttab_transfer(
goto copyback;
}
- guest_physmap_remove_page(d, _gfn(gop.mfn), _mfn(mfn), 0);
+ rc = guest_physmap_remove_page(d, _gfn(gop.mfn), _mfn(mfn), 0);
gnttab_flush_tlb(d);
+ if ( rc )
+ {
+ gdprintk(XENLOG_INFO,
+ "gnttab_transfer: can't remove GFN %"PRI_xen_pfn" (MFN %lx)\n",
+ gop.mfn, mfn);
+ gop.status = GNTST_general_error;
+ goto put_gfn_and_copyback;
+ }
/* Find the target domain. */
if ( unlikely((e = rcu_lock_domain_by_id(gop.domid)) == NULL) )
{
- put_gfn(d, gop.mfn);
gdprintk(XENLOG_INFO, "gnttab_transfer: can't find domain %d\n",
gop.domid);
- page->count_info &= ~(PGC_count_mask|PGC_allocated);
- free_domheap_page(page);
gop.status = GNTST_bad_domain;
- goto copyback;
+ goto put_gfn_and_copyback;
}
if ( xsm_grant_transfer(XSM_HOOK, d, e) )
{
- put_gfn(d, gop.mfn);
gop.status = GNTST_permission_denied;
unlock_and_copyback:
rcu_unlock_domain(e);
+ put_gfn_and_copyback:
+ put_gfn(d, gop.mfn);
page->count_info &= ~(PGC_count_mask|PGC_allocated);
free_domheap_page(page);
goto copyback;
@@ -1887,12 +1894,8 @@ gnttab_transfer(
"Transferee (d%d) has no headroom (tot %u, max %u)\n",
e->domain_id, e->tot_pages, e->max_pages);
- rcu_unlock_domain(e);
- put_gfn(d, gop.mfn);
- page->count_info &= ~(PGC_count_mask|PGC_allocated);
- free_domheap_page(page);
gop.status = GNTST_general_error;
- goto copyback;
+ goto unlock_and_copyback;
}
/* Okay, add the page to 'e'. */
@@ -1921,13 +1924,8 @@ gnttab_transfer(
if ( drop_dom_ref )
put_domain(e);
- rcu_unlock_domain(e);
-
- put_gfn(d, gop.mfn);
- page->count_info &= ~(PGC_count_mask|PGC_allocated);
- free_domheap_page(page);
gop.status = GNTST_general_error;
- goto copyback;
+ goto unlock_and_copyback;
}
page_list_add_tail(page, &e->page_list);
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -272,8 +272,12 @@ int guest_remove_page(struct domain *d,
mfn = get_gfn_query(d, gmfn, &p2mt);
if ( unlikely(p2m_is_paging(p2mt)) )
{
- guest_physmap_remove_page(d, _gfn(gmfn), mfn, 0);
+ rc = guest_physmap_remove_page(d, _gfn(gmfn), mfn, 0);
put_gfn(d, gmfn);
+
+ if ( rc )
+ return rc;
+
/* If the page hasn't yet been paged out, there is an
* actual page that needs to be released. */
if ( p2mt == p2m_ram_paging_out )
@@ -337,7 +341,9 @@ int guest_remove_page(struct domain *d,
return -ENXIO;
}
- if ( test_and_clear_bit(_PGT_pinned, &page->u.inuse.type_info) )
+ rc = guest_physmap_remove_page(d, _gfn(gmfn), mfn, 0);
+
+ if ( !rc && test_and_clear_bit(_PGT_pinned, &page->u.inuse.type_info) )
put_page_and_type(page);
/*
@@ -348,16 +354,14 @@ int guest_remove_page(struct domain *d,
* For this purpose (and to match populate_physmap() behavior), the page
* is kept allocated.
*/
- if ( !is_domain_direct_mapped(d) &&
+ if ( !rc && !is_domain_direct_mapped(d) &&
test_and_clear_bit(_PGC_allocated, &page->count_info) )
put_page(page);
- guest_physmap_remove_page(d, _gfn(gmfn), mfn, 0);
-
put_page(page);
put_gfn(d, gmfn);
- return 0;
+ return rc;
}
static void decrease_reservation(struct memop_args *a)
@@ -592,7 +596,8 @@ static long memory_exchange(XEN_GUEST_HA
gfn = mfn_to_gmfn(d, mfn);
/* Pages were unshared above */
BUG_ON(SHARED_M2P(gfn));
- guest_physmap_remove_page(d, _gfn(gfn), _mfn(mfn), 0);
+ if ( guest_physmap_remove_page(d, _gfn(gfn), _mfn(mfn), 0) )
+ domain_crash(d);
put_page(page);
}
@@ -1151,8 +1156,8 @@ long do_memory_op(unsigned long cmd, XEN
page = get_page_from_gfn(d, xrfp.gpfn, NULL, P2M_ALLOC);
if ( page )
{
- guest_physmap_remove_page(d, _gfn(xrfp.gpfn),
- _mfn(page_to_mfn(page)), 0);
+ rc = guest_physmap_remove_page(d, _gfn(xrfp.gpfn),
+ _mfn(page_to_mfn(page)), 0);
put_page(page);
}
else
--- a/xen/drivers/passthrough/arm/smmu.c
+++ b/xen/drivers/passthrough/arm/smmu.c
@@ -2786,9 +2786,7 @@ static int __must_check arm_smmu_unmap_p
if ( !is_domain_direct_mapped(d) )
return -EINVAL;
- guest_physmap_remove_page(d, _gfn(gfn), _mfn(gfn), 0);
-
- return 0;
+ return guest_physmap_remove_page(d, _gfn(gfn), _mfn(gfn), 0);
}
static const struct iommu_ops arm_smmu_iommu_ops = {
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -268,10 +268,6 @@ static inline int guest_physmap_add_page
return guest_physmap_add_entry(d, gfn, mfn, page_order, p2m_ram_rw);
}
-void guest_physmap_remove_page(struct domain *d,
- gfn_t gfn,
- mfn_t mfn, unsigned int page_order);
-
mfn_t gfn_to_mfn(struct domain *d, gfn_t gfn);
/*
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -561,10 +561,6 @@ static inline int guest_physmap_add_page
return guest_physmap_add_entry(d, gfn, mfn, page_order, p2m_ram_rw);
}
-/* Remove a page from a domain's p2m table */
-int guest_physmap_remove_page(struct domain *d,
- gfn_t gfn, mfn_t mfn, unsigned int page_order);
-
/* Set a p2m range as populate-on-demand */
int guest_physmap_mark_populate_on_demand(struct domain *d, unsigned long gfn,
unsigned int order);
--- a/xen/include/xen/p2m-common.h
+++ b/xen/include/xen/p2m-common.h
@@ -1,6 +1,7 @@
#ifndef _XEN_P2M_COMMON_H
#define _XEN_P2M_COMMON_H
+#include <xen/mm.h>
#include <public/vm_event.h>
/*
@@ -33,6 +34,11 @@ typedef enum {
/* NOTE: Assumed to be only 4 bits right now on x86. */
} p2m_access_t;
+/* Remove a page from a domain's p2m table */
+int __must_check
+guest_physmap_remove_page(struct domain *d, gfn_t gfn, mfn_t mfn,
+ unsigned int page_order);
+
/* Map MMIO regions in the p2m: start_gfn and nr describe the range in
* * the guest physical address space to map, starting from the machine
* * frame number mfn. */
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -554,7 +554,7 @@ int xenmem_add_to_physmap_one(struct dom
unsigned long idx, gfn_t gfn);
/* Returns 0 on success, or negative on error. */
-int guest_remove_page(struct domain *d, unsigned long gmfn);
+int __must_check guest_remove_page(struct domain *d, unsigned long gmfn);
#define RAM_TYPE_CONVENTIONAL 0x00000001
#define RAM_TYPE_RESERVED 0x00000002