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| author | H. Peter Anvin <hpa@zytor.com> | 2013-11-26 09:58:17 -0800 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2013-12-11 18:04:04 -0800 |
| commit | 88d17d136c21b8afb7d27e091cbb1f757ded80df (patch) | |
| tree | 741e512ba6fee4e8d9ecd0c2890057997b341f75 | |
| parent | 61f106ba8a5b2a7c2d9855291fd9e7f4a4d3143d (diff) | |
| download | syslinux-88d17d136c21b8afb7d27e091cbb1f757ded80df.tar.gz syslinux-88d17d136c21b8afb7d27e091cbb1f757ded80df.tar.xz syslinux-88d17d136c21b8afb7d27e091cbb1f757ded80df.zip | |
isolinux: Clear upper half of EDX before using
In checkin:
cb015497a4e4 isolinux: Update LBA in getlinsec loop
... we use EDX as a sector count, but the sector count is actually in
DX, and the upper half of EDX is uninitialized. If the BIOS enters
with a nonzero value in the upper half of EDX, this breaks horribly.
At least one set of BIOSes has been identified where if the LBA > 64K
then the upper half of EDX will be nonzero.
Reported-by: Carl Duff <cdrw2400@gmail.com>
Reported-by: Philip Müller <philm@manjaro.org>
Tested-by: Gerardo Exequiel Pozzi <vmlinuz386@yahoo.com.ar>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| -rw-r--r-- | core/isolinux.asm | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/core/isolinux.asm b/core/isolinux.asm index db6d2d42..dd0fa892 100644 --- a/core/isolinux.asm +++ b/core/isolinux.asm @@ -430,7 +430,7 @@ MaxLMA equ 384*1024 ; Reasonable limit (384K) call getlinsec pop eax pop cx - mov dx,cx + movzx edx,cx pop bp pop bx |