Hello Jike Song,
The patch 659643f7d814: "drm/i915/gvt/kvmgt: add vfio/mdev support to
KVMGT" from Dec 8, 2016, leads to the following static checker
warning:
drivers/gpu/drm/i915/gvt/kvmgt.c:969 intel_vgpu_ioctl()
warn: calling kfree() when 'caps.buf' is always NULL.
drivers/gpu/drm/i915/gvt/kvmgt.c
909 } else if (cmd == VFIO_DEVICE_GET_REGION_INFO) {
910 struct vfio_region_info info;
911 struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Set here.
912 int i, ret;
913 struct vfio_region_info_cap_sparse_mmap *sparse = NULL;
914 size_t size;
915 int nr_areas = 1;
916 int cap_type_id;
917
918 minsz = offsetofend(struct vfio_region_info, offset);
919
920 if (copy_from_user(&info, (void __user *)arg, minsz))
921 return -EFAULT;
922
923 if (info.argsz < minsz)
924 return -EINVAL;
925
926 switch (info.index) {
927 case VFIO_PCI_CONFIG_REGION_INDEX:
928 info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
929 info.size = INTEL_GVT_MAX_CFG_SPACE_SZ;
930 info.flags = VFIO_REGION_INFO_FLAG_READ |
931 VFIO_REGION_INFO_FLAG_WRITE;
932 break;
933 case VFIO_PCI_BAR0_REGION_INDEX:
934 info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
935 info.size = vgpu->cfg_space.bar[info.index].size;
936 if (!info.size) {
937 info.flags = 0;
938 break;
939 }
940
941 info.flags = VFIO_REGION_INFO_FLAG_READ |
942 VFIO_REGION_INFO_FLAG_WRITE;
943 break;
944 case VFIO_PCI_BAR1_REGION_INDEX:
945 info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
946 info.size = 0;
947 info.flags = 0;
948 break;
949 case VFIO_PCI_BAR2_REGION_INDEX:
950 info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
951 info.flags = VFIO_REGION_INFO_FLAG_CAPS |
952 VFIO_REGION_INFO_FLAG_MMAP |
953 VFIO_REGION_INFO_FLAG_READ |
954 VFIO_REGION_INFO_FLAG_WRITE;
955 info.size = gvt_aperture_sz(vgpu->gvt);
956
957 size = sizeof(*sparse) +
958 (nr_areas * sizeof(*sparse->areas));
959 sparse = kzalloc(size, GFP_KERNEL);
960 if (!sparse)
961 return -ENOMEM;
962
963 sparse->nr_areas = nr_areas;
964 cap_type_id = VFIO_REGION_INFO_CAP_SPARSE_MMAP;
965 sparse->areas[0].offset =
966 PAGE_ALIGN(vgpu_aperture_offset(vgpu));
967 sparse->areas[0].size = vgpu_aperture_sz(vgpu);
968 if (!caps.buf) {
^^^^^^^^
It's always NULL.
969 kfree(caps.buf);
Freeing NULL is pointless.
970 caps.buf = NULL;
971 caps.size = 0;
These were already zeroed out at the start of the function. What was
intended here? Probably you could just delete these lines.
972 }
973 break;
974
975 case VFIO_PCI_BAR3_REGION_INDEX ... VFIO_PCI_BAR5_REGION_INDEX:
regards,
dan carpenter
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