On Tue, 16 Feb 2021 10:34:32 -0800 Ben Widawsky <ben.widawsky@xxxxxxxxx> wrote: ... > > > diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c > > > index 237b956f0be0..4ca4f5afd9d2 100644 > > > --- a/drivers/cxl/mem.c > > > +++ b/drivers/cxl/mem.c > > > @@ -686,7 +686,11 @@ static int cxl_validate_cmd_from_user(struct cxl_mem *cxlm, > > > > > > memcpy(out_cmd, c, sizeof(*c)); > > > out_cmd->info.size_in = send_cmd->in.size; > > > - out_cmd->info.size_out = send_cmd->out.size; > > > + /* > > > + * XXX: out_cmd->info.size_out will be controlled by the driver, and the > > > + * specified number of bytes @send_cmd->out.size will be copied back out > > > + * to userspace. > > > + */ > > > > > > return 0; > > > } > > > > This deals with the buffer overflow being triggered from userspace. > > > > I'm still nervous. I really don't like assuming hardware will do the right > > thing and never send us more data than we expect. > > > > Given the check that it will fit in the target buffer is simple, > > I'd prefer to harden it and know we can't have a problem. > > > > Jonathan > > I'm working on hardening __cxl_mem_mbox_send_cmd now per your request. With > that, I think this solves the issue, right? Should do. Thanks, Jonathan
