[PATCH] drm/atomic: fix out of bounds read in for_each_*_in_state helpers

[Andrey Ryabinin]

for_each_*_in_state validate array index after
access to array elements, thus perform out of bounds read.

Fix this by validating index in the first place and read
array element iff validation was successful.

Fixes: df63b9994eaf ("drm/atomic: Add for_each_{connector,crtc,plane}_in_state helper macros")
Signed-off-by: Andrey Ryabinin <a.ryabinin at samsung.com>
---
 include/drm/drm_atomic.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index c1571034..3f13b91 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -77,26 +77,26 @@ int __must_check drm_atomic_async_commit(struct drm_atomic_state *state);
 
 #define for_each_connector_in_state(state, connector, connector_state, __i) \
 	for ((__i) = 0;							\
-	     (connector) = (state)->connectors[__i],			\
-	     (connector_state) = (state)->connector_states[__i],	\
-	     (__i) < (state)->num_connector;				\
+	     (__i) < (state)->num_connector &&				\
+	     ((connector) = (state)->connectors[__i],			\
+	     (connector_state) = (state)->connector_states[__i], 1); 	\
 	     (__i)++)							\
 		if (connector)
 
 #define for_each_crtc_in_state(state, crtc, crtc_state, __i)	\
 	for ((__i) = 0;						\
-	     (crtc) = (state)->crtcs[__i],			\
-	     (crtc_state) = (state)->crtc_states[__i],		\
-	     (__i) < (state)->dev->mode_config.num_crtc;	\
+	     (__i) < (state)->dev->mode_config.num_crtc &&	\
+	     ((crtc) = (state)->crtcs[__i],			\
+	     (crtc_state) = (state)->crtc_states[__i], 1);	\
 	     (__i)++)						\
 		if (crtc_state)
 
-#define for_each_plane_in_state(state, plane, plane_state, __i)	\
-	for ((__i) = 0;						\
-	     (plane) = (state)->planes[__i],			\
-	     (plane_state) = (state)->plane_states[__i],	\
-	     (__i) < (state)->dev->mode_config.num_total_plane;	\
-	     (__i)++)						\
+#define for_each_plane_in_state(state, plane, plane_state, __i)		\
+	for ((__i) = 0;							\
+	     (__i) < (state)->dev->mode_config.num_total_plane &&	\
+	     ((plane) = (state)->planes[__i],				\
+	     (plane_state) = (state)->plane_states[__i], 1);		\
+	     (__i)++)							\
 		if (plane_state)
 
 #endif /* DRM_ATOMIC_H_ */
-- 
2.4.1