hqdn3d: Fix out of array read in LOWPASS

CC:libav-stable@libav.org
Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavfilter/vf_hqdn3d.c

@@ -37,10 +37,10 @@
 #include "vf_hqdn3d.h"
 
 #define LUT_BITS (depth==16 ? 8 : 4)
-#define RIGHTSHIFT(a,b) (((a)+(((1<<(b))-1)>>1))>>(b))
-#define LOAD(x) ((depth==8 ? src[x] : AV_RN16A(src+(x)*2)) << (16-depth))
-#define STORE(x,val) (depth==8 ? dst[x] = RIGHTSHIFT(val, 16-depth)\
-                    : AV_WN16A(dst+(x)*2, RIGHTSHIFT(val, 16-depth)))
+#define LOAD(x) (((depth == 8 ? src[x] : AV_RN16A(src + (x) * 2)) << (16 - depth))\
+                 + (((1 << (16 - depth)) - 1) >> 1))
+#define STORE(x,val) (depth == 8 ? dst[x] = (val) >> (16 - depth) : \
+                                   AV_WN16A(dst + (x) * 2, (val) >> (16 - depth)))
 
 av_always_inline
 static uint32_t lowpass(int prev, int cur, int16_t *coef, int depth)

libavfilter/x86/vf_hqdn3d.asm

@@ -39,6 +39,7 @@ SECTION .text
 %endif
 %if %3 != 16
     shl    %1, 16-%3
+    add    %1, (1<<(15-%3))-1
 %endif
 %endmacro
 
@@ -86,7 +87,6 @@ ALIGN 16
     mov       [frameantq+xq*2], t0w
     movifnidn dstq, dstmp
 %if %1 != 16
-    add    t0d, (1<<(15-%1))-1
     shr    t0d, 16-%1 ; could eliminate this by storing from t0h, but only with some contraints on register allocation
 %endif
 %if %1 == 8