Re: [PATCH v4 2/3] io_uring: add IOURING_REGISTER_RESTRICTIONS opcode

[Stefano Garzarella <sgarzare@redhat.com>]

On Fri, Aug 14, 2020 at 01:42:15AM +0800, kernel test robot wrote:
> Hi Stefano,
> 
> I love your patch! Perhaps something to improve:
> 
> [auto build test WARNING on linus/master]
> [also build test WARNING on v5.8 next-20200813]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
> 
> url:    https://github.com/0day-ci/linux/commits/Stefano-Garzarella/io_uring-add-restrictions-to-support-untrusted-applications-and-guests/20200813-233653
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git dc06fe51d26efc100ac74121607c01a454867c91
> config: s390-randconfig-c003-20200813 (attached as .config)
> compiler: s390-linux-gcc (GCC) 9.3.0
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 
> 
> coccinelle warnings: (new ones prefixed by >>)
> 
> >> fs/io_uring.c:8516:7-14: WARNING opportunity for memdup_user

Yeah, I think make sense.

I'll use memdup_user() in the next version.

> 
> vim +8516 fs/io_uring.c
> 
>   8497	
>   8498	static int io_register_restrictions(struct io_ring_ctx *ctx, void __user *arg,
>   8499					    unsigned int nr_args)
>   8500	{
>   8501		struct io_uring_restriction *res;
>   8502		size_t size;
>   8503		int i, ret;
>   8504	
>   8505		/* We allow only a single restrictions registration */
>   8506		if (ctx->restricted)
>   8507			return -EBUSY;
>   8508	
>   8509		if (!arg || nr_args > IORING_MAX_RESTRICTIONS)
>   8510			return -EINVAL;
>   8511	
>   8512		size = array_size(nr_args, sizeof(*res));
>   8513		if (size == SIZE_MAX)
>   8514			return -EOVERFLOW;
>   8515	
> > 8516		res = kmalloc(size, GFP_KERNEL);
>   8517		if (!res)
>   8518			return -ENOMEM;
>   8519	
>   8520		if (copy_from_user(res, arg, size)) {
>   8521			ret = -EFAULT;
>   8522			goto out;
>   8523		}
>   8524	
>   8525		for (i = 0; i < nr_args; i++) {
>   8526			switch (res[i].opcode) {
>   8527			case IORING_RESTRICTION_REGISTER_OP:
>   8528				if (res[i].register_op >= IORING_REGISTER_LAST) {
>   8529					ret = -EINVAL;
>   8530					goto out;
>   8531				}
>   8532	
>   8533				__set_bit(res[i].register_op,
>   8534					  ctx->restrictions.register_op);
>   8535				break;
>   8536			case IORING_RESTRICTION_SQE_OP:
>   8537				if (res[i].sqe_op >= IORING_OP_LAST) {
>   8538					ret = -EINVAL;
>   8539					goto out;
>   8540				}
>   8541	
>   8542				__set_bit(res[i].sqe_op, ctx->restrictions.sqe_op);
>   8543				break;
>   8544			case IORING_RESTRICTION_SQE_FLAGS_ALLOWED:
>   8545				ctx->restrictions.sqe_flags_allowed = res[i].sqe_flags;
>   8546				break;
>   8547			case IORING_RESTRICTION_SQE_FLAGS_REQUIRED:
>   8548				ctx->restrictions.sqe_flags_required = res[i].sqe_flags;
>   8549				break;
>   8550			default:
>   8551				ret = -EINVAL;
>   8552				goto out;
>   8553			}
>   8554		}
>   8555	
>   8556		ctx->restricted = 1;
>   8557	
>   8558		ret = 0;
>   8559	out:
>   8560		/* Reset all restrictions if an error happened */
>   8561		if (ret != 0)
>   8562			memset(&ctx->restrictions, 0, sizeof(ctx->restrictions));
>   8563	
>   8564		kfree(res);
>   8565		return ret;
>   8566	}
>   8567	
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org