avcodec/mss4: Check input size against skip bits

[ffmpeg] / libavcodec / ac3dec.c

diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index 43b22b7654cfed23d6d7505c94ac9277142eeeb4..eaa327a3ee9446d9d59d6fcff99639699245fee1 100644 (file)
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -452,7 +452,7 @@ static int decode_exponents(AC3DecodeContext *s,
         prevexp += dexp[i] - 2;
         if (prevexp > 24U) {
             av_log(s->avctx, AV_LOG_ERROR, "exponent %d is out-of-range\n", prevexp);
-            return -1;
+            return AVERROR_INVALIDDATA;
         }
         switch (group_size) {
         case 4: dexps[j++] = prevexp;
@@ -1467,7 +1467,8 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data,
     int buf_size, full_buf_size = avpkt->size;
     AC3DecodeContext *s = avctx->priv_data;
     int blk, ch, err, offset, ret;
-    int got_independent_frame = 0;
+    int i;
+    int skip = 0, got_independent_frame = 0;
     const uint8_t *channel_map;
     uint8_t extended_channel_map[EAC3_MAX_CHANNELS];
     const SHORTFLOAT *output[AC3_MAX_CHANNELS];
@@ -1477,6 +1478,23 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data,
     s->superframe_size = 0;
 
     buf_size = full_buf_size;
+    for (i = 1; i < buf_size; i += 2) {
+        if (buf[i] == 0x77 || buf[i] == 0x0B) {
+            if ((buf[i] ^ buf[i-1]) == (0x77 ^ 0x0B)) {
+                i--;
+                break;
+            } else if ((buf[i] ^ buf[i+1]) == (0x77 ^ 0x0B)) {
+                break;
+            }
+        }
+    }
+    if (i >= buf_size)
+        return AVERROR_INVALIDDATA;
+    if (i > 10)
+        return i;
+    buf += i;
+    buf_size -= i;
+
     /* copy input buffer to decoder context to avoid reading past the end
        of the buffer, which can be caused by a damaged input stream. */
     if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
@@ -1637,6 +1655,11 @@ dependent_frame:
         AC3HeaderInfo hdr;
         int err;
 
+        if (buf_size - s->frame_size <= 16) {
+            skip = buf_size - s->frame_size;
+            goto skip;
+        }
+
         if ((ret = init_get_bits8(&s->gbc, buf + s->frame_size, buf_size - s->frame_size)) < 0)
             return ret;
 
@@ -1657,6 +1680,7 @@ dependent_frame:
             }
         }
     }
+skip:
 
     frame->decode_error_flags = err ? FF_DECODE_ERROR_INVALID_BITSTREAM : 0;
 
@@ -1796,9 +1820,9 @@ dependent_frame:
     *got_frame_ptr = 1;
 
     if (!s->superframe_size)
-        return FFMIN(full_buf_size, s->frame_size);
+        return FFMIN(full_buf_size, s->frame_size + skip);
 
-    return FFMIN(full_buf_size, s->superframe_size);
+    return FFMIN(full_buf_size, s->superframe_size + skip);
 }
 
 /**