On Mon, Nov 28, 2022 at 12:13:10PM +0100, Stefano Garzarella wrote: > On Mon, Nov 28, 2022 at 01:58:00PM +0300, Dan Carpenter wrote: > > On Mon, Nov 28, 2022 at 11:53:12AM +0100, Stefano Garzarella wrote: > > > On Mon, Nov 28, 2022 at 12:36:26AM -0800, Harshit Mogalapalli wrote: > > > > Add a limit to 'config->vq_num' which is user controlled data which > > > > comes from an vduse_ioctl to prevent large memory allocations. > > > > > > > > This is found using static analysis with smatch. > > > > > > > > Suggested-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > > > > Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx> > > > > --- > > > > v1->v2: Change title of the commit and description, add a limit to > > > > vq_num. > > > > > > > > Note: I think here 0xffff is the max size of vring = no: of vqueues. > > > > Only compile and boot tested. > > > > --- > > > > drivers/vdpa/vdpa_user/vduse_dev.c | 3 +++ > > > > 1 file changed, 3 insertions(+) > > > > > > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c > > > > index 35dceee3ed56..31017ebc4d7c 100644 > > > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c > > > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c > > > > @@ -1440,6 +1440,9 @@ static bool vduse_validate_config(struct vduse_dev_config *config) > > > > if (config->config_size > PAGE_SIZE) > > > > return false; > > > > > > > > + if (config->vq_num > 0xffff) > > > > > > What about using U16_MAX here? > > > > Where is the ->vq_num stored in a u16? I looked for this but didn't > > see it. > > I thought vq_num referred to the number of elements in the vq (like > .get_vq_num_max), since this patch wants to limit to 0xffff. > > But it actually refers to the number of virtqueue, so @Harshit why do we > limit it to 0xffff? > > Maybe we should explain it in the commit message or in a comment. > > Thanks, > Stefano This limit is somewhat arbitrary. However, currently virtio pci and ccw are limited to a 16 bit vq number. While MMIO isn't it is also isn't used with lots of VQs due to current lack of support for per-vq interrupts. Thus, the 0xffff limit on number of VQs corresponding to a 16-bit VQ number seems sufficient for now. Feel free to put the above in a code comment. -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
