Commit 55690c07 authored Jul 28, 2018 by Jinbum Park Committed by Jens Axboe Jul 28, 2018

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: Jinbum Park <jinb.park7@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent d43fdae7

drivers/block/pktcdvd.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -67,7 +67,7 @@
		#include <scsi/scsi.h>
		#include <linux/debugfs.h>
		#include <linux/device.h>

		#include <linux/nospec.h>
		#include <linux/uaccess.h>

		#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)
		return NULL;

		dev_minor = array_index_nospec(dev_minor, MAX_WRITERS);
		return pkt_devs[dev_minor];
		}

Admin message