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SubjectRe: [PATCH] sunvdc: Remove VLA usage
On Mon, Sep 24, 2018 at 8:19 PM, Kees Cook <keescook@chromium.org> wrote:
> On Wed, Sep 5, 2018 at 5:09 PM, Kees Cook <keescook@chromium.org> wrote:
>> In the quest to remove all stack VLA usage from the kernel[1], this
>> moves the math for cookie calculation into macros and allocates a fixed
>> size array for the maximum number of cookies and adds a runtime sanity check.
>> (Note that the size was always fixed, but just hidden from the compiler.)
>>
>> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>>
>> Signed-off-by: Kees Cook <keescook@chromium.org>
>
> Friendly ping. Jens, can you take this?

Dave, should this go via you instead? I'll take it via my tree if no
one else wants it...

Thanks,

-Kees

>
> Thanks!
>
> -Kees
>
>> ---
>> drivers/block/sunvdc.c | 14 ++++++++++----
>> 1 file changed, 10 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/block/sunvdc.c b/drivers/block/sunvdc.c
>> index 5ca56bfae63c..f68e9baffad7 100644
>> --- a/drivers/block/sunvdc.c
>> +++ b/drivers/block/sunvdc.c
>> @@ -36,6 +36,10 @@ MODULE_VERSION(DRV_MODULE_VERSION);
>> #define VDC_TX_RING_SIZE 512
>> #define VDC_DEFAULT_BLK_SIZE 512
>>
>> +#define MAX_XFER_BLKS (128 * 1024)
>> +#define MAX_XFER_SIZE (MAX_XFER_BLKS / VDC_DEFAULT_BLK_SIZE)
>> +#define MAX_RING_COOKIES ((MAX_XFER_BLKS / PAGE_SIZE) + 2)
>> +
>> #define WAITING_FOR_LINK_UP 0x01
>> #define WAITING_FOR_TX_SPACE 0x02
>> #define WAITING_FOR_GEN_CMD 0x04
>> @@ -450,7 +454,7 @@ static int __send_request(struct request *req)
>> {
>> struct vdc_port *port = req->rq_disk->private_data;
>> struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
>> - struct scatterlist sg[port->ring_cookies];
>> + struct scatterlist sg[MAX_RING_COOKIES];
>> struct vdc_req_entry *rqe;
>> struct vio_disk_desc *desc;
>> unsigned int map_perm;
>> @@ -458,6 +462,9 @@ static int __send_request(struct request *req)
>> u64 len;
>> u8 op;
>>
>> + if (WARN_ON(port->ring_cookies > MAX_RING_COOKIES))
>> + return -EINVAL;
>> +
>> map_perm = LDC_MAP_SHADOW | LDC_MAP_DIRECT | LDC_MAP_IO;
>>
>> if (rq_data_dir(req) == READ) {
>> @@ -984,9 +991,8 @@ static int vdc_port_probe(struct vio_dev *vdev, const struct vio_device_id *id)
>> goto err_out_free_port;
>>
>> port->vdisk_block_size = VDC_DEFAULT_BLK_SIZE;
>> - port->max_xfer_size = ((128 * 1024) / port->vdisk_block_size);
>> - port->ring_cookies = ((port->max_xfer_size *
>> - port->vdisk_block_size) / PAGE_SIZE) + 2;
>> + port->max_xfer_size = MAX_XFER_SIZE;
>> + port->ring_cookies = MAX_RING_COOKIES;
>>
>> err = vio_ldc_alloc(&port->vio, &vdc_ldc_cfg, port);
>> if (err)
>> --
>> 2.17.1
>>
>>
>> --
>> Kees Cook
>> Pixel Security
>
>
>
> --
> Kees Cook
> Pixel Security



--
Kees Cook
Pixel Security

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