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 <[email protected]>
---
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);
return pkt_devs[dev_minor];
}
--
1.9.1
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 <[email protected]>
> ---
> 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 <[email protected]>
Thanks
--
Gustavo
Jinbum,
I just noticed this patch does not apply to linux-next.
Please try again, but this time work from linux-next rather than from a stable tree.
Thanks
--
Gustavo
On 07/27/2018 09:47 PM, Gustavo A. R. Silva wrote:
>
>
> 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 <[email protected]>
>> ---
>> 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 <[email protected]>
>
> Thanks
> --
> Gustavo
>