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

[Jens Axboe <axboe@kernel.dk>]

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?

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 8fe7ad18a709..f615a791a7cd 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -205,7 +205,6 @@ 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);
 
@@ -213,11 +212,13 @@ static int nvme_execute_user_rq(struct request *req, void __user *meta_buffer,
 
 	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