On Wed, May 31, 2023 at 09:45:38PM -0700, Sukrut Bellary wrote:
> On Fri, May 19, 2023 at 03:57:59PM -0700, Sukrut Bellary wrote:
> > On Fri, May 19, 2023 at 11:39:59AM +0100, Srinivas Kandagatla wrote:
> > >
> > >
> > > On 19/05/2023 11:22, Dan Carpenter wrote:
> > > > > ----------------------->cut<---------------------------
> > > > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> > > > > index f60bbf99485c..3fdd326e1ae8 100644
> > > > > --- a/drivers/misc/fastrpc.c
> > > > > +++ b/drivers/misc/fastrpc.c
> > > > > @@ -1891,7 +1891,8 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl,
> > > > > char __user *argp)
> > > > > &args[0]);
> > > > > if (err) {
> > > > > dev_err(dev, "mmap error (len 0x%08llx)\n", buf->size);
> > > > > - goto err_invoke;
> > > > > + fastrpc_buf_free(buf);
> > > > > + return err;
> > > > > }
> > > > >
> > > > > /* update the buffer to be able to deallocate the memory on the DSP
> > > > > */
> > > > > @@ -1930,11 +1931,7 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl,
> > > > > char __user *argp)
> > > > > return 0;
> > > > >
> > > > > err_assign:
> > > > > - fastrpc_req_munmap_impl(fl, buf);
> > > > > -err_invoke:
> > > > > - fastrpc_buf_free(buf);
> > > > > -
> > > > > - return err;
> > > > > + return fastrpc_req_munmap_impl(fl, buf);
> > > >
> > > > This will return success if copy_to_user() fails.
> > > >
> > > that is true, using return value of fastrpc_req_munmap_impl does not really
> > > make sense here we should just return err in either case to the user.
> > >
> >
>
> I have one follow-up question before I send the v2 patch.
> With the following approach, I do see one issue.
>
> ----------------------->cut<---------------------------
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index f60bbf99485c..3fdd326e1ae8 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -1891,7 +1891,8 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl,
> char __user *argp)
> &args[0]);
> if (err) {
> dev_err(dev, "mmap error (len 0x%08llx)\n", buf->size);
> - goto err_invoke;
> + fastrpc_buf_free(buf);
> + return err;
> }
>
> /* update the buffer to be able to deallocate the memory on the DSP */
> @@ -1930,11 +1931,7 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl,
> char __user *argp)
> return 0;
>
> err_assign:
> - fastrpc_req_munmap_impl(fl, buf);
> -err_invoke:
> - fastrpc_buf_free(buf);
> -
> - return err;
> + fastrpc_req_munmap_impl(fl, buf);
> + return err;
> }
> ----------------------->cut<---------------------------
>
> In this, if qcom_scm_assign_mem() fails, the buf is not added to the list.
> But the call to fastrpc_req_munmap_impl() tries to delete the buf
> from the list.
>
> To avoid this, we can use the following approach.
The list is initialized in __fastrpc_buf_alloc().
INIT_LIST_HEAD(&buf->node);
So calling list_del(&buf->node); is fine. It's not necessary but it's
not harmful.
regards,
dan carpenter
