Hi Gerd,
Thank you for the patch.
On Tuesday, 11 September 2018 09:59:18 EEST Gerd Hoffmann wrote:
> Create variable for the list length limit. Serves as documentation,
> also allows to make it a module parameter if needed.
>
> Also add a total size limit.
>
> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> ---
> drivers/dma-buf/udmabuf.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
> index 0cf7e85585..cb99a7886a 100644
> --- a/drivers/dma-buf/udmabuf.c
> +++ b/drivers/dma-buf/udmabuf.c
> @@ -12,6 +12,9 @@
> #include <linux/shmem_fs.h>
> #include <linux/udmabuf.h>
>
> +static int list_limit = 1024; /* udmabuf_create_list->count limit */
> +static int size_limit_mb = 64; /* total dmabuf size, in megabytes */
static const int maybe ? Or size_t for the size limit and unsigned int for the
limit on the number of entries, as they can't be negative ?
Why those specific values ?
> struct udmabuf {
> pgoff_t pagecount;
> struct page **pages;
> @@ -123,7 +126,7 @@ static long udmabuf_create(struct const
> udmabuf_create_list *head, struct file *memfd = NULL;
> struct udmabuf *ubuf;
> struct dma_buf *buf;
> - pgoff_t pgoff, pgcnt, pgidx, pgbuf;
> + pgoff_t pgoff, pgcnt, pgidx, pgbuf, pglimit;
> struct page *page;
> int seals, ret = -EINVAL;
> u32 i, flags;
> @@ -132,12 +135,15 @@ static long udmabuf_create(struct const
> udmabuf_create_list *head, if (!ubuf)
> return -ENOMEM;
>
> + pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
> for (i = 0; i < head->count; i++) {
> if (!IS_ALIGNED(list[i].offset, PAGE_SIZE))
> goto err_free_ubuf;
> if (!IS_ALIGNED(list[i].size, PAGE_SIZE))
> goto err_free_ubuf;
> ubuf->pagecount += list[i].size >> PAGE_SHIFT;
> + if (ubuf->pagecount > pglimit)
> + goto err_free_ubuf;
> }
> ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(struct page *),
> GFP_KERNEL);
> @@ -227,7 +233,7 @@ static long udmabuf_ioctl_create_list(struct file *filp,
> unsigned long arg)
>
> if (copy_from_user(&head, (void __user *)arg, sizeof(head)))
> return -EFAULT;
> - if (head.count > 1024)
> + if (head.count > list_limit)
> return -EINVAL;
> lsize = sizeof(struct udmabuf_create_item) * head.count;
> list = memdup_user((void __user *)(arg + sizeof(head)), lsize);
--
Regards,
Laurent Pinchart
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