Re: [PATCH v2 2/4] nvme: reject invalid pr_read_keys() num_keys values

Christoph Hellwig
2025-12-01T07:27:31Z

On Mon, Dec 01, 2025 at 07:11:31AM +0000, Chaitanya Kulkarni wrote:
> On 11/27/25 07:54, Stefan Hajnoczi wrote:
> > The pr_read_keys() interface has a u32 num_keys parameter. The NVMe
> > Reservation Report command has a u32 maximum length. Reject num_keys
> > values that are too large to fit.
> >
> > This will become important when pr_read_keys() is exposed to untrusted
> > userspace via an <linux/pr.h> ioctl.
> >
> > Signed-off-by: Stefan Hajnoczi<stefanha@redhat.com>
> > ---
> > drivers/nvme/host/pr.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/nvme/host/pr.c b/drivers/nvme/host/pr.c
> > index ca6a74607b139..156a2ae1fac2e 100644
> > --- a/drivers/nvme/host/pr.c
> > +++ b/drivers/nvme/host/pr.c
> > @@ -233,6 +233,10 @@ static int nvme_pr_read_keys(struct block_device *bdev,
> > int ret, i;
> > bool eds;
> >
> > + /* Check that keys fit into u32 rse_len */
> > + if (num_keys > (U32_MAX - sizeof(*rse)) / sizeof(rse->regctl_eds[0]))
> > + return -EINVAL;
>
> de-referencing res in res->regctl_eds[0] is safe in this patch ?

sizeof does not dereference pointers in the expression.