diff --git a/libavcodec/lagarith.c b/libavcodec/lagarith.c
index 7220648bc4..ca4ab5cc53 100644
--- a/libavcodec/lagarith.c
+++ b/libavcodec/lagarith.c
@@ -409,6 +409,9 @@ output_zeros:
         if (zero_run) {
             zero_run = 0;
             i += esc_count;
+            if (i >  end - dst ||
+                i >= src_end - src)
+                return AVERROR_INVALIDDATA;
             memcpy(dst, src, i);
             dst += i;
             l->zeros_rem = lag_calc_zero_run(src[i]);