utvideodec: Prevent possible signed overflow
authorGanesh Ajjanagadde <gajjanag@gmail.com>
Tue, 23 Feb 2016 04:21:58 +0000 (23:21 -0500)
committerLuca Barbato <lu_zero@gentoo.org>
Thu, 13 Apr 2017 11:37:10 +0000 (13:37 +0200)
Doing slice_end - slice_start is unsafe and can lead to undefined behavior
until slice_end has been properly sanitized.

Reviewed-by: Ronald S. Bultje <rsbultje@gmail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanag@gmail.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
libavcodec/utvideodec.c

index 808e3be..2aaf861 100644 (file)
@@ -361,12 +361,12 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
         slice_end   = 0;
         for (j = 0; j < c->slices; j++) {
             slice_end   = bytestream2_get_le32u(&gb);
-            slice_size  = slice_end - slice_start;
-            if (slice_end < 0 || slice_size < 0 ||
+            if (slice_end < 0 || slice_end < slice_start ||
                 bytestream2_get_bytes_left(&gb) < slice_end) {
                 av_log(avctx, AV_LOG_ERROR, "Incorrect slice size\n");
                 return AVERROR_INVALIDDATA;
             }
+            slice_size  = slice_end - slice_start;
             slice_start = slice_end;
             max_slice_size = FFMAX(max_slice_size, slice_size);
         }