On Fri, Apr 05, 2013 at 12:56:07PM +0200, Markus Armbruster wrote: > Stefan Hajnoczi <stefa...@redhat.com> writes: > > > What is the highest addressable sector on an empty CD-ROM? Nothing is > > addressable so produce an error. > > > > This patch prevents a divide-by-zero in ide_set_sector() since > > s->sectors and s->heads would be 0. Not to mention that a sector=-1 > > argument would be nonsense. > > > > Note that WIN_READ_NATIVE_MAX can be triggered using hdparm -N 1024 > > /dev/cdrom. The LBA bit will be set to 1 though, so the only easy way > > to go down the ide_set_sector() CHS code path which divides by zero is > > to comment out the s->select & 0x40 case for testing. > > Suggests you did that. > > Have you tried the reproducer with a physical drive? Does it fail the > command when empty, too?
Believe it or not, I don't have access to an ATAPI CD-ROM drive. Would you be able to try out hdparm -N 1024 /dev/cdrom? Note that READ NATIVE MAX is optional, real drives may not implement it since it seems geared towards the Host Protected Area feature which makes no sense on CD-ROMs. (The idea is a reserved area on the disk where system data can be stored and the OS will not touch it.) Stefan
