x86: check for canonical address before doing page walks ... as there doesn't really exists any valid mapping for them. Particularly in the case of do_page_walk() this also avoids returning non-NULL for such invalid input. Suggested-by: Andrew Cooper Signed-off-by: Jan Beulich --- a/xen/arch/x86/x86_64/mm.c +++ b/xen/arch/x86/x86_64/mm.c @@ -73,7 +73,7 @@ void *do_page_walk(struct vcpu *v, unsig l2_pgentry_t l2e, *l2t; l1_pgentry_t l1e, *l1t; - if ( is_hvm_vcpu(v) ) + if ( is_hvm_vcpu(v) || !is_canonical_address(addr) ) return NULL; l4t = map_domain_page(mfn); --- a/xen/arch/x86/x86_64/traps.c +++ b/xen/arch/x86/x86_64/traps.c @@ -170,6 +170,8 @@ void show_page_walk(unsigned long addr) l1_pgentry_t l1e, *l1t; printk("Pagetable walk from %016lx:\n", addr); + if ( !is_canonical_address(addr) ) + return; l4t = map_domain_page(mfn); l4e = l4t[l4_table_offset(addr)];