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Commit b205ca57 authored by Daniel Vetter's avatar Daniel Vetter
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drm/i915: Use unsigned for overflow checks in execbuf 



There's actually no real risk since we already check for stricter
constraints earlier (using UINT_MAX / sizeof (struct
drm_i915_gem_exec_object2) as the limit). But in eb_create we use
signed integers, which steals a factor of 2. Luckily struct
drm_i915_gem_exec_object2 for this to not matter.

Still, be consistent and use unsigned integers.

Similar use unsinged integers when checking for overflows in the
relocation entry processing.

I've also added a new subtests to igt/gem_reloc_overflow to also
test for overflowing args->buffer_count values.

v2: Give the variables again tighter scope to make it clear that the
computation is purely local and doesn't leak out to the 2nd block.
Requested by Chris Wilson.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 955382f3

drivers/gpu/drm/i915/i915_gem_execbuffer.c

+6 −6
Original line number Diff line number Diff line
@@ -48,15 +48,15 @@ eb_create(struct drm_i915_gem_execbuffer2 *args, struct i915_address_space *vm) 
	struct eb_vmas *eb = NULL;



	if (args->flags & I915_EXEC_HANDLE_LUT) {

		int size = args->buffer_count;

		unsigned size = args->buffer_count;

		size *= sizeof(struct i915_vma *);

		size += sizeof(struct eb_vmas);

		eb = kmalloc(size, GFP_TEMPORARY | __GFP_NOWARN | __GFP_NORETRY);

	}



	if (eb == NULL) {

		int size = args->buffer_count;

		int count = PAGE_SIZE / sizeof(struct hlist_head) / 2;

		unsigned size = args->buffer_count;

		unsigned count = PAGE_SIZE / sizeof(struct hlist_head) / 2;

		BUILD_BUG_ON_NOT_POWER_OF_2(PAGE_SIZE / sizeof(struct hlist_head));

		while (count > 2*size)

			count >>= 1;
@@ -667,7 +667,7 @@ i915_gem_execbuffer_relocate_slow(struct drm_device *dev, 
	bool need_relocs;

	int *reloc_offset;

	int i, total, ret;

	int count = args->buffer_count;

	unsigned count = args->buffer_count;



	if (WARN_ON(list_empty(&eb->vmas)))

		return 0;
@@ -818,8 +818,8 @@ validate_exec_list(struct drm_i915_gem_exec_object2 *exec, 
		   int count)

{

	int i;

	int relocs_total = 0;

	int relocs_max = INT_MAX / sizeof(struct drm_i915_gem_relocation_entry);

	unsigned relocs_total = 0;

	unsigned relocs_max = UINT_MAX / sizeof(struct drm_i915_gem_relocation_entry);



	for (i = 0; i < count; i++) {

		char __user *ptr = to_user_ptr(exec[i].relocs_ptr);