RE: [PATCH v4 3/5] nvme: refactor nvme_submit_user_cmd()

Clay Mayers
2022-05-05T19:30:14Z

On 5/5/22 12:11 PM, Jens Axboe wrote:
> On 5/5/22 1:03 PM, Jens Axboe wrote:
> > On 5/5/22 12:37 PM, Clay Mayers wrote:
> >>> From: Kanchan Joshi
> >>> Sent: Wednesday, May 4, 2022 11:06 PM
> >>> ---
> >>
> >>> drivers/nvme/host/ioctl.c | 47 ++++++++++++++++++++++++++++++++++---
> --
> >>> 1 file changed, 42 insertions(+), 5 deletions(-)
> >>>
> >>> +static int nvme_execute_user_rq(struct request *req, void __user
> >>> *meta_buffer,
> >>> + unsigned meta_len, u64 *result)
> >>> +{
> >>> + struct bio *bio = req->bio;
> >>> + bool write = bio_op(bio) == REQ_OP_DRV_OUT;
> >>
> >> I'm getting a NULL ptr access on the first
> ioctl(NVME_IOCTL_ADMIN64_CMD)
> >> I send - it has no ubuffer so I think there's no req->bio.
> >
> > Does this work?

It did not! Same null ptr deref at nearly if not the same location.
I didn't investigate to see the line of code since you had sent v2.

>
> This might be better, though you'd only notice if you had integrity
> enabled. Christoph, I'm folding this in with patch 3...
>
>
> diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
> index 8fe7ad18a709..3d827789b536 100644
> --- a/drivers/nvme/host/ioctl.c
> +++ b/drivers/nvme/host/ioctl.c
> @@ -21,9 +21,13 @@ static void __user *nvme_to_user_ptr(uintptr_t ptrval)
>
> static inline void *nvme_meta_from_bio(struct bio *bio)
> {
> - struct bio_integrity_payload *bip = bio_integrity(bio);
> + if (bio) {
> + struct bio_integrity_payload *bip = bio_integrity(bio);
>
> - return bip ? bvec_virt(bip->bip_vec) : NULL;
> + return bip ? bvec_virt(bip->bip_vec) : NULL;
> + }
> +
> + return NULL;
> }
>
> /*
> @@ -205,19 +209,20 @@ static int nvme_execute_user_rq(struct request *req,
> void __user *meta_buffer,
> unsigned meta_len, u64 *result)
> {
> struct bio *bio = req->bio;
> - bool write = bio_op(bio) == REQ_OP_DRV_OUT;
> - int ret;
> void *meta = nvme_meta_from_bio(bio);
> + int ret;
>
> ret = nvme_execute_passthru_rq(req);
>
> if (result)
> *result = le64_to_cpu(nvme_req(req)->result.u64);
> - if (meta && !ret && !write) {
> - if (copy_to_user(meta_buffer, meta, meta_len))
> + if (meta) {
> + bool write = bio_op(bio) == REQ_OP_DRV_OUT;
> +
> + if (!ret && !write && copy_to_user(meta_buffer, meta,
> meta_len))
> ret = -EFAULT;
> + kfree(meta);
> }
> - kfree(meta);
> if (bio)
> blk_rq_unmap_user(bio);
> blk_mq_free_request(req);
>
> --
> Jens Axboe

This does work and got me past the null ptr segfault.

Clay.