On 07/27/2018 09:30 PM, Jinbum Park wrote: > User controls @dev_minor which to be used as index of pkt_devs. > So, It can be exploited via Spectre-like attack. (speculative execution) > > This kind of attack leaks address of pkt_devs, [1] > It leads an attacker to bypass security mechanism such as KASLR. > > So sanitize @dev_minor before using it to prevent attack. > > [1] https://github.com/jinb-park/linux-exploit/ > tree/master/exploit-remaining-spectre-gadget/leak_pkt_devs.c > > Signed-off-by: Jinbum Park <jinb.park7@xxxxxxxxx> > --- > v2: Fix coding style by Gustavo. > > drivers/block/pktcdvd.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c > index c61d20c..8ec2eaa 100644 > --- a/drivers/block/pktcdvd.c > +++ b/drivers/block/pktcdvd.c > @@ -67,8 +67,8 @@ > #include <scsi/scsi.h> > #include <linux/debugfs.h> > #include <linux/device.h> > - > #include <linux/uaccess.h> > +#include <linux/nospec.h> > > #define DRIVER_NAME "pktcdvd" > > @@ -2231,6 +2231,7 @@ static struct pktcdvd_device *pkt_find_dev_from_minor(unsigned int dev_minor) > { > if (dev_minor >= MAX_WRITERS) > return NULL; > + dev_minor = array_index_nospec(dev_minor, MAX_WRITERS); Adding a blank line here would be even better. > return pkt_devs[dev_minor]; > } > > Acked-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> Thanks -- Gustavo
