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ide: refuse WIN_READ_NATIVE_MAX on empty device

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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 <stefanha@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2013-04-05 11:51:01 +02:00
parent c09b437b5f
commit aad64f3193
1 changed files with 4 additions and 0 deletions
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4
hw/ide/core.c
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@ -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;