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Commit 1692cd60 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Sanity check the computed size and base of stolen memory 



Just do a quick check that the stolen memory address range doesn't
overflow our chosen integer type.

v2: Add add_overflows() to utils with the promise that gcc7 can do this
better than C and then maybe it will have a proper definition in core.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170130134721.5159-1-chris@chris-wilson.co.uk


Reviewed-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
parent c8847387

drivers/gpu/drm/i915/i915_gem_stolen.c

+1 −1
Original line number Diff line number Diff line
@@ -189,7 +189,7 @@ static dma_addr_t i915_stolen_to_dma(struct drm_i915_private *dev_priv) 
		base = tom - tseg_size - ggtt->stolen_size;

	}



	if (base == 0)

	if (base == 0 || add_overflows(base, ggtt->stolen_size))

		return 0;



	/* make sure we don't clobber the GTT if it's within stolen memory */

drivers/gpu/drm/i915/i915_utils.h

+11 −0
Original line number Diff line number Diff line
@@ -25,6 +25,17 @@ 
#ifndef __I915_UTILS_H

#define __I915_UTILS_H



#if GCC_VERSION >= 70000

#define add_overflows(A, B) \

	__builtin_add_overflow_p((A), (B), (typeof((A) + (B)))0)

#else

#define add_overflows(A, B) ({ \

	typeof(A) a = (A); \

	typeof(B) b = (B); \

	a + b < a; \

})

#endif



#define range_overflows(start, size, max) ({ \

	typeof(start) start__ = (start); \

	typeof(size) size__ = (size); \