Hi Keqian,

url:    
https://github.com/0day-ci/linux/commits/Keqian-Zhu/vfio-iommu_type1-Some-fixes-and-optimization/20201210-154322
 
base:   https://github.com/awilliam/linux-vfio.git  next
config: x86_64-randconfig-m001-20201215 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
Reported-by: Dan Carpenter <[email protected]>

smatch warnings:
drivers/vfio/vfio_iommu_type1.c:648 vfio_iommu_type1_pin_pages() warn: variable 
dereferenced before check 'iommu' (see line 640)

vim +/iommu +648 drivers/vfio/vfio_iommu_type1.c

a54eb55045ae9b3 Kirti Wankhede  2016-11-17  631  static int 
vfio_iommu_type1_pin_pages(void *iommu_data,
95fc87b44104d9a Kirti Wankhede  2020-05-29  632                                 
      struct iommu_group *iommu_group,
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  633                                 
      unsigned long *user_pfn,
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  634                                 
      int npage, int prot,
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  635                                 
      unsigned long *phys_pfn)
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  636  {
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  637         struct vfio_iommu 
*iommu = iommu_data;
95fc87b44104d9a Kirti Wankhede  2020-05-29  638         struct vfio_group 
*group;
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  639         int i, j, ret;
2b172c0ea2a6daf Keqian Zhu      2020-12-10 @640         unsigned long pgshift = 
__ffs(iommu->pgsize_bitmap);
                                                                                
      ^^^^^^^^^^^^^^^^^^^^
The patch introduces a new dereference.

a54eb55045ae9b3 Kirti Wankhede  2016-11-17  641         unsigned long 
remote_vaddr;
2b172c0ea2a6daf Keqian Zhu      2020-12-10  642         unsigned long 
bitmap_offset;
2b172c0ea2a6daf Keqian Zhu      2020-12-10  643         unsigned long 
*bitmap_added;
2b172c0ea2a6daf Keqian Zhu      2020-12-10  644         dma_addr_t iova;
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  645         struct vfio_dma *dma;
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  646         bool do_accounting;
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  647  
a54eb55045ae9b3 Kirti Wankhede  2016-11-17 @648         if (!iommu || !user_pfn 
|| !phys_pfn)
                                                            ^^^^^^
Checked too late.

a54eb55045ae9b3 Kirti Wankhede  2016-11-17  649                 return -EINVAL;
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  650  
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  651         /* Supported for v2 
version only */
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  652         if (!iommu->v2)
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  653                 return -EACCES;
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  654  
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  655         
mutex_lock(&iommu->lock);
a54eb55045ae9b3 Kirti Wankhede  2016-11-17  656  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected] 

Attachment: .config.gz
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