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Commit 55690c07 authored by Jinbum Park's avatar Jinbum Park Committed by Jens Axboe
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pktcdvd: Fix possible Spectre-v1 for pkt_devs 

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: default avatarJinbum Park <jinb.park7@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d43fdae7

drivers/block/pktcdvd.c

+3 −1
Original line number Original line Diff line number Diff line
@@ -67,7 +67,7 @@ 
#include <scsi/scsi.h>

#include <scsi/scsi.h>

#include <linux/debugfs.h>

#include <linux/debugfs.h>

#include <linux/device.h>

#include <linux/device.h>



#include <linux/nospec.h>

#include <linux/uaccess.h>

#include <linux/uaccess.h>





#define DRIVER_NAME	"pktcdvd"

#define DRIVER_NAME	"pktcdvd"
@@ -2254,6 +2254,8 @@ static struct pktcdvd_device *pkt_find_dev_from_minor(unsigned int dev_minor) 
{

{

	if (dev_minor >= MAX_WRITERS)

	if (dev_minor >= MAX_WRITERS)

		return NULL;

		return NULL;



	dev_minor = array_index_nospec(dev_minor, MAX_WRITERS);

	return pkt_devs[dev_minor];

	return pkt_devs[dev_minor];

}

}