fpga: fix potential null pointer deref in fpga_mgr_test_img_load_sgt()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: fpga: fix potential null pointer deref in fpga_mgr_test_img_load_sgt() fpga_mgr_test_img_load_sgt() allocates memory for sgt using kunit_kzalloc() however it does not check if the allocation failed. It then passes sgt to sg_alloc_table(), which passes it to __sg_alloc_table(). This function calls memset() on sgt in an attempt to zero it out. If the allocation fails then sgt will be NULL and the memset will trigger a NULL pointer dereference. Fix this by checking the allocation with KUNIT_ASSERT_NOT_ERR_OR_NULL().

References

• https://git.kernel.org/stable/c/e69e2cfd8b38d9463a250e153ef4963a604d61e9
• https://git.kernel.org/stable/c/8b2230ac7ff0aeb2441132df638a82ab124f8624
• https://git.kernel.org/stable/c/eb4c74eaa6e2d15f3bbd32941c9d2a25b29a718d
• https://git.kernel.org/stable/c/6ebf1982038af12f3588417e4fd0417d2551da28