From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [PATCH] x86/EDD: check MBR for BIOS magic before considering signature valid Date: Wed, 30 May 2012 17:48:00 +0100 Message-ID: References: <4FC65A930200007800086F39@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4FC65A930200007800086F39@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 30/05/2012 16:36, "Jan Beulich" wrote: > Signed-off-by: Jan Beulich Acked-by: Keir Fraser > --- a/xen/arch/x86/boot/edd.S > +++ b/xen/arch/x86/boot/edd.S > @@ -53,12 +53,16 @@ edd_mbr_sig_read: > jc edd_mbr_sig_done # on failure, we're done. > cmpb $0, %ah # some BIOSes do not set CF > jne edd_mbr_sig_done # on failure, we're done. > + cmpw $0xaa55, bootsym(boot_edd_info)+0x1fe > + jne .Ledd_mbr_sig_next > movl bootsym(boot_edd_info)+EDD_MBR_SIG_OFFSET,%eax > movb %dl, (%bx) # store BIOS drive number > movl %eax, 4(%bx) # store signature from MBR > incb bootsym(boot_mbr_signature_nr) # note that we stored > something > - incb %dl # increment to next device > addw $8, %bx # increment sig buffer ptr > +.Ledd_mbr_sig_next: > + incb %dl # increment to next device > + jz edd_mbr_sig_done > cmpb $EDD_MBR_SIG_MAX,bootsym(boot_mbr_signature_nr) > jb edd_mbr_sig_read > edd_mbr_sig_done: > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel