Coverity: iommufd_vfio_iommu_get_info(): Code maintainability issues

Coverity: iommufd_vfio_iommu_get_info(): Code maintainability issues

[coverity-bot]

Hello!

This is an experimental semi-automated report about issues detected by
Coverity from a scan of next-20221102 as part of the linux-next scan project:
https://scan.coverity.com/projects/linux-next-weekly-scan

You're getting this email because you were associated with the identified
lines of code (noted below) that were touched by commits:

  Mon Oct 31 13:37:58 2022 -0300
    32c328dc9b73 ("iommufd: vfio container FD ioctl compatibility")

Coverity reported the following:

*** CID 1527093:  Code maintainability issues  (UNUSED_VALUE)
/drivers/iommu/iommufd/vfio_compat.c: 411 in iommufd_vfio_iommu_get_info()
405     	 */
406     	if (info.argsz >= total_cap_size)
407     		info.cap_offset = sizeof(info);
408     	info.argsz = total_cap_size;
409     	info.flags |= VFIO_IOMMU_INFO_CAPS;
410     	if (copy_to_user(arg, &info, minsz))
vvv     CID 1527093:  Code maintainability issues  (UNUSED_VALUE)
vvv     Assigning value "-14" to "rc" here, but that stored value is overwritten before it can be used.
411     		rc = -EFAULT;
412     	rc = 0;
413
414     out_put:
415     	up_read(&ioas->iopt.iova_rwsem);
416     	iommufd_put_object(&ioas->obj);

If this is a false positive, please let us know so we can mark it as
such, or teach the Coverity rules to be smarter. If not, please make
sure fixes get into linux-next. :) For patches fixing this, please
include these lines (but double-check the "Fixes" first):

Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1527093 ("Code maintainability issues")
Fixes: 32c328dc9b73 ("iommufd: vfio container FD ioctl compatibility")

This looks more like a "goto" is missing after the -EFAULT assignment?

Thanks for your attention!

-- 
Coverity-bot

Re: Coverity: iommufd_vfio_iommu_get_info(): Code maintainability issues

[Jason Gunthorpe]

On Wed, Nov 02, 2022 at 12:55:21PM -0700, coverity-bot wrote:

> /drivers/iommu/iommufd/vfio_compat.c: 411 in iommufd_vfio_iommu_get_info()
> 405     	 */
> 406     	if (info.argsz >= total_cap_size)
> 407     		info.cap_offset = sizeof(info);
> 408     	info.argsz = total_cap_size;
> 409     	info.flags |= VFIO_IOMMU_INFO_CAPS;
> 410     	if (copy_to_user(arg, &info, minsz))
> vvv     CID 1527093:  Code maintainability issues  (UNUSED_VALUE)
> vvv     Assigning value "-14" to "rc" here, but that stored value is overwritten before it can be used.
> 411     		rc = -EFAULT;
> 412     	rc = 0;
> 413
> 414     out_put:
> 415     	up_read(&ioas->iopt.iova_rwsem);
> 416     	iommufd_put_object(&ioas->obj);
> 
> If this is a false positive, please let us know so we can mark it as
> such, or teach the Coverity rules to be smarter. If not, please make
> sure fixes get into linux-next. :) For patches fixing this, please
> include these lines (but double-check the "Fixes" first):

Yes, this is legit, we already fixed it

Thanks,
Jason