Make sure MFN read from pte is valid before accessing the page info structure
associated with it. Drop guest-to-machine-physical translation from ptwr code.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Index: 2007-05-14/xen/arch/x86/mm.c
==================================================================---
2007-05-14.orig/xen/arch/x86/mm.c 2007-05-14 13:43:50.000000000 +0200
+++ 2007-05-14/xen/arch/x86/mm.c 2007-05-14 13:44:25.000000000 +0200
@@ -3238,13 +3238,14 @@ static int ptwr_emulated_update(
/* We are looking only for read-only mappings of p.t. pages. */
ASSERT((l1e_get_flags(pte) & (_PAGE_RW|_PAGE_PRESENT)) ==
_PAGE_PRESENT);
+ ASSERT(mfn_valid(mfn));
ASSERT((page->u.inuse.type_info & PGT_type_mask) ==
PGT_l1_page_table);
ASSERT((page->u.inuse.type_info & PGT_count_mask) != 0);
ASSERT(page_get_owner(page) == d);
/* Check the new PTE. */
nl1e = l1e_from_intpte(val);
- if ( unlikely(!get_page_from_l1e(gl1e_to_ml1e(d, nl1e), d)) )
+ if ( unlikely(!get_page_from_l1e(nl1e, d)) )
{
if ( (CONFIG_PAGING_LEVELS >= 3) && is_pv_32bit_domain(d)
&&
(bytes == 4) && (addr & 4) && !do_cmpxchg
&&
@@ -3270,7 +3271,7 @@ static int ptwr_emulated_update(
adjust_guest_l1e(nl1e, d);
/* Checked successfully: do the update (write or cmpxchg). */
- pl1e = map_domain_page(page_to_mfn(page));
+ pl1e = map_domain_page(mfn);
pl1e = (l1_pgentry_t *)((unsigned long)pl1e + (addr & ~PAGE_MASK));
if ( do_cmpxchg )
{
@@ -3285,21 +3286,21 @@ static int ptwr_emulated_update(
if ( !okay )
{
unmap_domain_page(pl1e);
- put_page_from_l1e(gl1e_to_ml1e(d, nl1e), d);
+ put_page_from_l1e(nl1e, d);
return X86EMUL_CMPXCHG_FAILED;
}
}
else
{
ol1e = *pl1e;
- if ( !UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, page_to_mfn(page), v) )
+ if ( !UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, mfn, v) )
BUG();
}
unmap_domain_page(pl1e);
/* Finally, drop the old PTE. */
- put_page_from_l1e(gl1e_to_ml1e(d, ol1e), d);
+ put_page_from_l1e(ol1e, d);
return X86EMUL_OKAY;
}
@@ -3365,17 +3366,13 @@ int ptwr_do_page_fault(struct vcpu *v, u
LOCK_BIGLOCK(d);
- /*
- * Attempt to read the PTE that maps the VA being accessed. By checking for
- * PDE validity in the L2 we avoid many expensive fixups in __get_user().
- */
+ /* Attempt to read the PTE that maps the VA being accessed. */
guest_get_eff_l1e(v, addr, &pte);
- if ( !(l1e_get_flags(pte) & _PAGE_PRESENT) )
- goto bail;
page = l1e_get_page(pte);
/* We are looking only for read-only mappings of p.t. pages. */
if ( ((l1e_get_flags(pte) & (_PAGE_PRESENT|_PAGE_RW)) != _PAGE_PRESENT)
||
+ !mfn_valid(l1e_get_pfn(pte)) ||
((page->u.inuse.type_info & PGT_type_mask) !=
PGT_l1_page_table) ||
((page->u.inuse.type_info & PGT_count_mask) == 0) ||
(page_get_owner(page) != d) )
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