From 564dd3f0f40008be8943af59686c0e8c4d67dd08 Mon Sep 17 00:00:00 2001 From: Andreas Cadhalpun Date: Fri, 15 Jan 2016 00:17:10 +0100 Subject: [PATCH] mpeg4videodec: silence ubsan warning s->ac_val[0][0] is of type 'int16_t [16]', but points into a larger buffer. Here it is used as base pointer to find the correct position in the larger buffer by adding 's->block_index[n] * 16' and thus as 'int16_t *'. This fixes clang's ubsan runtime error: index out of bounds for type 'int16_t [16]' Fixes: test_case.mp4 Found-by: Tyson Smith Reviewed-by: Michael Niedermayer Signed-off-by: Andreas Cadhalpun --- libavcodec/mpeg4videodec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c index 133adbb6fe..527cbe96c5 100644 --- a/libavcodec/mpeg4videodec.c +++ b/libavcodec/mpeg4videodec.c @@ -67,7 +67,7 @@ void ff_mpeg4_pred_ac(MpegEncContext *s, int16_t *block, int n, int dir) int8_t *const qscale_table = s->current_picture.qscale_table; /* find prediction */ - ac_val = s->ac_val[0][0] + s->block_index[n] * 16; + ac_val = &s->ac_val[0][0][0] + s->block_index[n] * 16; ac_val1 = ac_val; if (s->ac_pred) { if (dir == 0) {