From: Jan Beulich Date: Thu, 31 May 2012 08:18:13 +0000 (+0200) Subject: x86/EDD: check MBR for BIOS magic before considering signature valid X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~8371 X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https:/%22bookmarks://%22Dat/%22http:/www.example.com/cgi/%22https:/%22bookmarks:/%22Dat?a=commitdiff_plain;h=9f78a9e4d9a64d75ef74b2ebbde7b79ba4045381;p=xen.git x86/EDD: check MBR for BIOS magic before considering signature valid Signed-off-by: Jan Beulich Acked-by: Keir Fraser --- diff --git a/xen/arch/x86/boot/edd.S b/xen/arch/x86/boot/edd.S index 59874ce4c6..2c8df8ccc8 100644 --- 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: