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pktcdvd: Fix possible Spectre-v1 for pkt_devs 

[ Upstream commit 55690c07b4 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Jinbum Park 2018-07-28 13:20:44 +09:00 committed by Greg Kroah-Hartman
parent 5f91efc475
commit 7141f97cdd
1 changed files with 3 additions and 1 deletions
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4
drivers/block/pktcdvd.c
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@ -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"
@ -2231,6 +2231,8 @@ 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];
}