drm/i915: Check for integer truncation on the configuration of ttm place

There is an impedance mismatch between the first/last valid page
frame number of ttm place in unsigned and our memory/page accounting in
unsigned long.
As the object size is under the control of userspace, we have to be prudent
and catch the conversion errors.
To catch the implicit truncation as we switch from unsigned long to
unsigned, we use overflows_type check and report E2BIG or overflow_type
prior to the operation.

v3: Not to change execution inside a macro. (Mauro)
    Add safe_conversion_gem_bug_on() macro and remove temporal
    SAFE_CONVERSION() macro.
v4: Fix unhandled GEM_BUG_ON() macro call from safe_conversion_gem_bug_on()
v6: Fix to follow general use case for GEM_BUG_ON(). (Jani)
v7: Fix to use WARN_ON() macro where GEM_BUG_ON() macro was used. (Jani)
v8: Replace safe_conversion() with check_assign() (Kees)
v14: Split one macro of assignment with checking of overflow to two steps,
     first overflow check, and second assignment.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com> (v2)
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org> (v3)
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com> (v5)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221228192252.917299-4-gwan-gyeong.mun@intel.com

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index af1378d93baafecc199a7a503439e9566cf1e29b..5f3abe1bb7d7e970cc8949c3d9cc33fc0ca023c5 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -140,13 +140,16 @@ i915_ttm_place_from_region(const struct intel_memory_region *mr,
        if (flags & I915_BO_ALLOC_CONTIGUOUS)
                place->flags |= TTM_PL_FLAG_CONTIGUOUS;
        if (offset != I915_BO_INVALID_OFFSET) {
+               WARN_ON(overflows_type(offset >> PAGE_SHIFT, place->fpfn));
                place->fpfn = offset >> PAGE_SHIFT;
+               WARN_ON(overflows_type(place->fpfn + (size >> PAGE_SHIFT), place->lpfn));
                place->lpfn = place->fpfn + (size >> PAGE_SHIFT);
        } else if (mr->io_size && mr->io_size < mr->total) {
                if (flags & I915_BO_ALLOC_GPU_ONLY) {
                        place->flags |= TTM_PL_FLAG_TOPDOWN;
                } else {
                        place->fpfn = 0;
+                       WARN_ON(overflows_type(mr->io_size >> PAGE_SHIFT, place->lpfn));
                        place->lpfn = mr->io_size >> PAGE_SHIFT;
                }
        }

diff --git a/drivers/gpu/drm/i915/intel_region_ttm.c b/drivers/gpu/drm/i915/intel_region_ttm.c
index cf89d0c2a2d9456f8912123244d8c9c7a73a9aee..7f0ec35af09854d1981544f9c97282409b16a12a 100644 (file)
--- a/drivers/gpu/drm/i915/intel_region_ttm.c
+++ b/drivers/gpu/drm/i915/intel_region_ttm.c
@@ -209,13 +209,25 @@ intel_region_ttm_resource_alloc(struct intel_memory_region *mem,
        if (flags & I915_BO_ALLOC_CONTIGUOUS)
                place.flags |= TTM_PL_FLAG_CONTIGUOUS;
        if (offset != I915_BO_INVALID_OFFSET) {
+               if (WARN_ON(overflows_type(offset >> PAGE_SHIFT, place.fpfn))) {
+                       ret = -E2BIG;
+                       goto out;
+               }
                place.fpfn = offset >> PAGE_SHIFT;
+               if (WARN_ON(overflows_type(place.fpfn + (size >> PAGE_SHIFT), place.lpfn))) {
+                       ret = -E2BIG;
+                       goto out;
+               }
                place.lpfn = place.fpfn + (size >> PAGE_SHIFT);
        } else if (mem->io_size && mem->io_size < mem->total) {
                if (flags & I915_BO_ALLOC_GPU_ONLY) {
                        place.flags |= TTM_PL_FLAG_TOPDOWN;
                } else {
                        place.fpfn = 0;
+                       if (WARN_ON(overflows_type(mem->io_size >> PAGE_SHIFT, place.lpfn))) {
+                               ret = -E2BIG;
+                               goto out;
+                       }
                        place.lpfn = mem->io_size >> PAGE_SHIFT;
                }
        }
@@ -224,6 +236,8 @@ intel_region_ttm_resource_alloc(struct intel_memory_region *mem,
        mock_bo.bdev = &mem->i915->bdev;
 
        ret = man->func->alloc(man, &mock_bo, &place, &res);
+
+out:
        if (ret == -ENOSPC)
                ret = -ENXIO;
        if (!ret)