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@xxxxxxxxxxxx>
> >
> > Use the helper that checks for overflows internally instead of manually
> > calculating the size of the new array.
> >
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
>
> 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;
+
+ 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;
}
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