On Wed, Jun 17, 2020 at 07:57:20AM +0530, Souptick Joarder wrote:
> There is a bug, when get_user_pages() failed but partially pinned
> pages are not unpinned. Fixed it.
>
> Also, int is more appropriate type for rv. Changed it.
>
> Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
> Cc: John Hubbard <jhubbard@xxxxxxxxxx>
> Cc: Bharath Vedartham <linux.bhar@xxxxxxxxx>
> Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> drivers/staging/kpc2000/kpc_dma/fileops.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
> index 8975346..b136353 100644
> --- a/drivers/staging/kpc2000/kpc_dma/fileops.c
> +++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
> @@ -35,7 +35,7 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
> unsigned long iov_base, size_t iov_len)
> {
> unsigned int i = 0;
> - long rv = 0;
> + int rv = 0;
> struct kpc_dma_device *ldev;
> struct aio_cb_data *acd;
> DECLARE_COMPLETION_ONSTACK(done);
> @@ -193,6 +193,10 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
> put_page(acd->user_pages[i]);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> err_get_user_pages:
> + if (rv > 0) {
> + for (i = 0; i < rv; i++)
> + put_pages(acd->user_pages[i])
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> + }
This isn't a complete fix. "rv" is the negative error code but here we
are returning a positive value on this path. Also it's ugly to have
same put_page() loop repeated twice.
It would be better to write it like this:
rv = get_user_pages(iov_base, acd->page_count, FOLL_TOUCH | FOLL_WRITE | FOLL_GET, acd->user_pages, NULL);
mmap_read_unlock(current->mm); /* release the semaphore */
if (rv < 0)
goto free_pages;
if (rv != acd->page_count) {
acd->page_count = rv;
rv = -EFAULT;
goto put_pages;
}
...
put_pages:
for (i = 0 ; i < acd->page_count ; i++)
put_pages(acd->user_pages[i]);
free_pages:
kfree(acd->user_pages);
regards,
dan carpenter
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