From aad64f3193cbdc3741d10afa0237b6833e46e94e Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Fri, 5 Apr 2013 11:51:01 +0200 Subject: ide: refuse WIN_READ_NATIVE_MAX on empty device 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. Signed-off-by: Stefan Hajnoczi Reviewed-by: Markus Armbruster --- hw/ide/core.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'hw/ide/core.c') diff --git a/hw/ide/core.c b/hw/ide/core.c index 87d67b7bcb..c7a80413be 100644 --- a/hw/ide/core.c +++ b/hw/ide/core.c @@ -1262,6 +1262,10 @@ void ide_exec_cmd(IDEBus *bus, uint32_t val) lba48 = 1; /* fall through */ case WIN_READ_NATIVE_MAX: + /* Refuse if no sectors are addressable (e.g. medium not inserted) */ + if (s->nb_sectors == 0) { + goto abort_cmd; + } ide_cmd_lba48_transform(s, lba48); ide_set_sector(s, s->nb_sectors - 1); s->status = READY_STAT | SEEK_STAT; -- cgit v1.2.1