Re: [linux-next PATCH v4] drivers/virt/fsl_hypervisor: Fix error handling path

John Hubbard
2020-09-01T21:30:24Z

On 9/1/20 2:21 PM, Souptick Joarder wrote:
> First, when memory allocation for sg_list_unaligned failed, there
> is a bug of calling put_pages() as we haven't pinned any pages.
>
> Second, if get_user_pages_fast() failed we should unpin num_pinned
> pages.
>
> This will address both.
>
> As part of these changes, minor update in documentation.
>
> Fixes: 6db7199407ca ("drivers/virt: introduce Freescale hypervisor
> management driver")
> Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> ---

This looks good to me.

thanks,
--
John Hubbard
NVIDIA

> v2:
> Added review tag.
>
> v3:
> Address review comment on v2 from John.
> Added review tag.
>
> v4:
> Address another set of review comments from John.
>
> drivers/virt/fsl_hypervisor.c | 17 ++++++++---------
> 1 file changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/virt/fsl_hypervisor.c b/drivers/virt/fsl_hypervisor.c
> index 1b0b11b..46ee0a0 100644
> --- a/drivers/virt/fsl_hypervisor.c
> +++ b/drivers/virt/fsl_hypervisor.c
> @@ -157,7 +157,7 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
>
> unsigned int i;
> long ret = 0;
> - int num_pinned; /* return value from get_user_pages() */
> + int num_pinned = 0; /* return value from get_user_pages_fast() */
> phys_addr_t remote_paddr; /* The next address in the remote buffer */
> uint32_t count; /* The number of bytes left to copy */
>
> @@ -174,7 +174,7 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
> return -EINVAL;
>
> /*
> - * The array of pages returned by get_user_pages() covers only
> + * The array of pages returned by get_user_pages_fast() covers only
> * page-aligned memory. Since the user buffer is probably not
> * page-aligned, we need to handle the discrepancy.
> *
> @@ -224,7 +224,7 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
>
> /*
> * 'pages' is an array of struct page pointers that's initialized by
> - * get_user_pages().
> + * get_user_pages_fast().
> */
> pages = kcalloc(num_pages, sizeof(struct page *), GFP_KERNEL);
> if (!pages) {
> @@ -241,7 +241,7 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
> if (!sg_list_unaligned) {
> pr_debug("fsl-hv: could not allocate S/G list\n");
> ret = -ENOMEM;
> - goto exit;
> + goto free_pages;
> }
> sg_list = PTR_ALIGN(sg_list_unaligned, sizeof(struct fh_sg_list));
>
> @@ -250,7 +250,6 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
> num_pages, param.source != -1 ? FOLL_WRITE : 0, pages);
>
> if (num_pinned != num_pages) {
> - /* get_user_pages() failed */
> pr_debug("fsl-hv: could not lock source buffer\n");
> ret = (num_pinned < 0) ? num_pinned : -EFAULT;
> goto exit;
> @@ -292,13 +291,13 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
> virt_to_phys(sg_list), num_pages);
>
> exit:
> - if (pages) {
> - for (i = 0; i < num_pages; i++)
> - if (pages[i])
> - put_page(pages[i]);
> + if (pages && (num_pinned > 0)) {
> + for (i = 0; i < num_pinned; i++)
> + put_page(pages[i]);
> }
>
> kfree(sg_list_unaligned);
> +free_pages:
> kfree(pages);
>
> if (!ret)
>