Hello Jonathan Cavitt,
Commit 05da7d9f717b ("drm/i915/gem: Downgrade stolen lmem setup
warning") from Apr 22, 2024 (linux-next), leads to the following
Smatch static checker warning:
drivers/gpu/drm/i915/intel_memory_region.c:371 intel_memory_regions_hw_probe()
error: potential NULL/IS_ERR bug 'mem'
drivers/gpu/drm/i915/intel_memory_region.c
327 int intel_memory_regions_hw_probe(struct drm_i915_private *i915)
328 {
329 int err, i;
330
331 for (i = 0; i < ARRAY_SIZE(i915->mm.regions); i++) {
332 struct intel_memory_region *mem = ERR_PTR(-ENODEV);
333 u16 type, instance;
334
335 if (!HAS_REGION(i915, i))
336 continue;
337
338 type = intel_region_map[i].class;
339 instance = intel_region_map[i].instance;
340 switch (type) {
341 case INTEL_MEMORY_SYSTEM:
342 if (IS_DGFX(i915))
343 mem = i915_gem_ttm_system_setup(i915, type,
344 instance);
345 else
346 mem = i915_gem_shmem_setup(i915, type,
347 instance);
348 break;
349 case INTEL_MEMORY_STOLEN_LOCAL:
350 mem = i915_gem_stolen_lmem_setup(i915, type, instance);
i915_gem_stolen_lmem_setup() used to only return error pointers but now it
returns NULL as well.
351 if (!IS_ERR(mem))
352 i915->mm.stolen_region = mem;
353 break;
354 case INTEL_MEMORY_STOLEN_SYSTEM:
355 mem = i915_gem_stolen_smem_setup(i915, type, instance);
356 if (!IS_ERR(mem))
357 i915->mm.stolen_region = mem;
358 break;
359 default:
360 continue;
361 }
362
363 if (IS_ERR(mem)) {
364 err = PTR_ERR(mem);
365 drm_err(&i915->drm,
366 "Failed to setup region(%d) type=%d\n",
367 err, type);
368 goto out_cleanup;
369 }
370
--> 371 mem->id = i;
^^^^^^^^^^^^
Potentially leading to a NULL dereference here?
372 i915->mm.regions[i] = mem;
373 }
374
375 for (i = 0; i < ARRAY_SIZE(i915->mm.regions); i++) {
376 struct intel_memory_region *mem = i915->mm.regions[i];
377 u64 region_size, io_size;
regards,
dan carpenter
