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

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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: Chris 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: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
This commit is contained in:
Chris Wilson 2017-01-30 13:47:21 +00:00
parent c88473878d
commit 1692cd60d9
2 changed files with 12 additions and 1 deletions
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2
drivers/gpu/drm/i915/i915_gem_stolen.c
View File

@ -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 */

11
drivers/gpu/drm/i915/i915_utils.h
View File

@ -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); \