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);elsenew = 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;}