libFuzzer found an undefined behavior (#DIV/0!) in ide_set_sector() when using a CD-ROM (reproducer available on the BugLink):
UndefinedBehaviorSanitizer:DEADLYSIGNAL ==12163==ERROR: UndefinedBehaviorSanitizer: FPE on unknown address 0x5616279cffdc (pc 0x5616279cffdc bp 0x7ffcdaabae90 sp 0x7ffcdaabae30 T12163) Fix by initializing the CD-ROM number of sectors in ide_dev_initfn(). Reported-by: Alexander Bulekov <[email protected]> Fixes: b2df431407 ("ide scsi: Mess with geometry only for hard disk devices") BugLink: https://bugs.launchpad.net/qemu/+bug/1887309 Signed-off-by: Philippe Mathieu-Daudé <[email protected]> --- hw/ide/qdev.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/hw/ide/qdev.c b/hw/ide/qdev.c index 27ff1f7f66..6ce7fc317c 100644 --- a/hw/ide/qdev.c +++ b/hw/ide/qdev.c @@ -201,6 +201,15 @@ static void ide_dev_initfn(IDEDevice *dev, IDEDriveKind kind, Error **errp) errp)) { return; } + } else { + uint64_t nb_sectors; + + blk_get_geometry(dev->conf.blk, &nb_sectors); + if (!nb_sectors) { + error_setg(errp, "CD-ROM size can not be zero"); + return; + } + dev->conf.secs = nb_sectors; } if (!blkconf_apply_backend_options(&dev->conf, kind == IDE_CD, kind != IDE_CD, errp)) { -- 2.21.3
