From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [PATCH] x86/HVM: linear address must be canonical for the whole accessed range Date: Fri, 20 Sep 2013 16:30:02 +0100 Message-ID: References: <523C64CA02000078000F4EE7@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VN2ev-0002TE-UE for xen-devel@lists.xenproject.org; Fri, 20 Sep 2013 15:30:18 +0000 Received: by mail-wi0-f169.google.com with SMTP id hj3so9458278wib.2 for ; Fri, 20 Sep 2013 08:30:16 -0700 (PDT) In-Reply-To: <523C64CA02000078000F4EE7@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich , xen-devel List-Id: xen-devel@lists.xenproject.org On 20/09/2013 14:07, "Jan Beulich" wrote: > ... rather than just for the first byte. > > While at it, also > - make the real mode case at least dpo a wrap around check > - drop the mis-named "gpf" label (we're not generating faults here) > and use in-place returns instead > > Signed-off-by: Jan Beulich Acked-by: Keir Fraser > --- a/xen/arch/x86/hvm/hvm.c > +++ b/xen/arch/x86/hvm/hvm.c > @@ -1931,8 +1931,7 @@ int hvm_virtual_to_linear_addr( > unsigned int addr_size, > unsigned long *linear_addr) > { > - unsigned long addr = offset; > - uint32_t last_byte; > + unsigned long addr = offset, last_byte; > > if ( !(current->arch.hvm_vcpu.guest_cr[0] & X86_CR0_PE) ) > { > @@ -1941,6 +1940,9 @@ int hvm_virtual_to_linear_addr( > * Certain of them are not done in native real mode anyway. > */ > addr = (uint32_t)(addr + reg->base); > + last_byte = (uint32_t)addr + bytes - 1; > + if ( last_byte < addr ) > + return 0; > } > else if ( addr_size != 64 ) > { > @@ -1952,17 +1954,17 @@ int hvm_virtual_to_linear_addr( > { > case hvm_access_read: > if ( (reg->attr.fields.type & 0xa) == 0x8 ) > - goto gpf; /* execute-only code segment */ > + return 0; /* execute-only code segment */ > break; > case hvm_access_write: > if ( (reg->attr.fields.type & 0xa) != 0x2 ) > - goto gpf; /* not a writable data segment */ > + return 0; /* not a writable data segment */ > break; > default: > break; > } > > - last_byte = offset + bytes - 1; > + last_byte = (uint32_t)offset + bytes - 1; > > /* Is this a grows-down data segment? Special limit check if so. */ > if ( (reg->attr.fields.type & 0xc) == 0x4 ) > @@ -1973,10 +1975,10 @@ int hvm_virtual_to_linear_addr( > > /* Check first byte and last byte against respective bounds. */ > if ( (offset <= reg->limit) || (last_byte < offset) ) > - goto gpf; > + return 0; > } > else if ( (last_byte > reg->limit) || (last_byte < offset) ) > - goto gpf; /* last byte is beyond limit or wraps 0xFFFFFFFF */ > + return 0; /* last byte is beyond limit or wraps 0xFFFFFFFF */ > > /* > * Hardware truncates to 32 bits in compatibility mode. > @@ -1993,15 +1995,14 @@ int hvm_virtual_to_linear_addr( > if ( (seg == x86_seg_fs) || (seg == x86_seg_gs) ) > addr += reg->base; > > - if ( !is_canonical_address(addr) ) > - goto gpf; > + last_byte = addr + bytes - 1; > + if ( !is_canonical_address(addr) || last_byte < addr || > + !is_canonical_address(last_byte) ) > + return 0; > } > > *linear_addr = addr; > return 1; > - > - gpf: > - return 0; > } > > /* On non-NULL return, we leave this function holding an additional > > >