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
Cc: Joonas Lahtinen
---
drivers/gpu/drm/i915/i915_gem_stolen.c | 2 +-
drivers/gpu/drm/i915/i915_utils.h | 7 +++
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c
b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 42bbc4b04fd6..f3abdc27c5dd 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -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 */
diff --git a/drivers/gpu/drm/i915/i915_utils.h
b/drivers/gpu/drm/i915/i915_utils.h
index 34020873e1f6..69e00c94ee13 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -25,6 +25,13 @@
#ifndef __I915_UTILS_H
#define __I915_UTILS_H
+#if GCC_VERSION >= 7
+#define add_overflows(A, B) \
+ __builtin_add_overflow_p((A), (B), (typeof((A) + (B)))0)
+#else
+#define add_overflows(A, B) ((A) + (B) < (A))
+#endif
+
#define range_overflows(start, size, max) ({ \
typeof(start) start__ = (start); \
typeof(size) size__ = (size); \
--
2.11.0
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