diff mbox series

[3/8] vhost: vringh: use krealloc_array()

Message ID 20201027121725.24660-4-brgl@bgdev.pl
State New
Headers show
Series slab: provide and use krealloc_array() | expand

Commit Message

Bartosz Golaszewski Oct. 27, 2020, 12:17 p.m. UTC
From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Use the helper that checks for overflows internally instead of manually
calculating the size of the new array.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/vhost/vringh.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Bartosz Golaszewski Oct. 27, 2020, 4:58 p.m. UTC | #1
On Tue, Oct 27, 2020 at 5:50 PM Joe Perches <joe@perches.com> wrote:
>

> On Tue, 2020-10-27 at 11:28 -0400, Michael S. Tsirkin wrote:

> > On Tue, Oct 27, 2020 at 01:17:20PM +0100, Bartosz Golaszewski wrote:

> > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

> > >

> > > Use the helper that checks for overflows internally instead of manually

> > > calculating the size of the new array.

> > >

> > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

> >

> > No problem with the patch, it does introduce some symmetry in the code.

>

> Perhaps more symmetry by using kmemdup

> ---

>  drivers/vhost/vringh.c | 23 ++++++++++-------------

>  1 file changed, 10 insertions(+), 13 deletions(-)

>

> diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c

> index 8bd8b403f087..99222a3651cd 100644

> --- a/drivers/vhost/vringh.c

> +++ b/drivers/vhost/vringh.c

> @@ -191,26 +191,23 @@ static int move_to_indirect(const struct vringh *vrh,

>  static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp)

>  {

>         struct kvec *new;

> -       unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2;

> +       size_t new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2;

> +       size_t size;

>

>         if (new_num < 8)

>                 new_num = 8;

>

> -       flag = (iov->max_num & VRINGH_IOV_ALLOCATED);

> -       if (flag)

> -               new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp);

> -       else {

> -               new = kmalloc_array(new_num, sizeof(struct iovec), gfp);

> -               if (new) {

> -                       memcpy(new, iov->iov,

> -                              iov->max_num * sizeof(struct iovec));

> -                       flag = VRINGH_IOV_ALLOCATED;

> -               }

> -       }

> +       if (unlikely(check_mul_overflow(new_num, sizeof(struct iovec), &size)))

> +               return -ENOMEM;

> +


The whole point of using helpers such as kmalloc_array() is not doing
these checks manually.

Bartosz

> +       if (iov->max_num & VRINGH_IOV_ALLOCATED)

> +               new = krealloc(iov->iov, size, gfp);

> +       else

> +               new = kmemdup(iov->iov, size, gfp);

>         if (!new)

>                 return -ENOMEM;

>         iov->iov = new;

> -       iov->max_num = (new_num | flag);

> +       iov->max_num = new_num | VRINGH_IOV_ALLOCATED;

>         return 0;

>  }

>

>

>
diff mbox series

Patch

diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
index 8bd8b403f087..08a0e1c842df 100644
--- a/drivers/vhost/vringh.c
+++ b/drivers/vhost/vringh.c
@@ -198,7 +198,8 @@  static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp)
 
 	flag = (iov->max_num & VRINGH_IOV_ALLOCATED);
 	if (flag)
-		new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp);
+		new = krealloc_array(iov->iov, new_num,
+				     sizeof(struct iovec), gfp);
 	else {
 		new = kmalloc_array(new_num, sizeof(struct iovec), gfp);
 		if (new) {