On Mon, Sep 24, 2018 at 8:19 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > On Wed, Sep 5, 2018 at 5:09 PM, Kees Cook <keescook@xxxxxxxxxxxx> 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@xxxxxxxxxxxxxx >> >> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > 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
