vp3: fix oob read for negative tokens and memleaks on error.

(cherry picked from commit 8370e426e4)

Fixes: #189
Chromium-Bug: 101172,100465
CVE-2011-3892

Signed-off-by: Reinhard Tartler <siretart@tauware.de>

libavcodec/vp3.c

@@ -45,6 +45,7 @@
 #define FRAGMENT_PIXELS 8
 
 static av_cold int vp3_decode_end(AVCodecContext *avctx);
+static void vp3_decode_flush(AVCodecContext *avctx);
 
 //FIXME split things out into their own arrays
 typedef struct Vp3Fragment {
@@ -890,7 +891,7 @@ static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
             /* decode a VLC into a token */
             token = get_vlc2(gb, vlc_table, 11, 3);
             /* use the token to get a zero run, a coefficient, and an eob run */
-            if (token <= 6) {
+            if ((unsigned) token <= 6U) {
                 eob_run = eob_run_base[token];
                 if (eob_run_get_bits[token])
                     eob_run += get_bits(gb, eob_run_get_bits[token]);
@@ -908,7 +909,7 @@ static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
                     coeff_i        += eob_run;
                     eob_run = 0;
                 }
-            } else {
+            } else if (token >= 0) {
                 bits_to_get = coeff_get_bits[token];
                 if (bits_to_get)
                     bits_to_get = get_bits(gb, bits_to_get);
@@ -942,6 +943,10 @@ static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
                 for (i = coeff_index+1; i <= coeff_index+zero_run; i++)
                     s->num_coded_frags[plane][i]--;
                 coeff_i++;
+            } else {
+                av_log(s->avctx, AV_LOG_ERROR,
+                       "Invalid token %d\n", token);
+                return -1;
             }
     }
 
@@ -991,6 +996,8 @@ static int unpack_dct_coeffs(Vp3DecodeContext *s, GetBitContext *gb)
     /* unpack the Y plane DC coefficients */
     residual_eob_run = unpack_vlcs(s, gb, &s->dc_vlc[dc_y_table], 0,
         0, residual_eob_run);
+    if (residual_eob_run < 0)
+        return residual_eob_run;
 
     /* reverse prediction of the Y-plane DC coefficients */
     reverse_dc_prediction(s, 0, s->fragment_width[0], s->fragment_height[0]);
@@ -998,8 +1005,12 @@ static int unpack_dct_coeffs(Vp3DecodeContext *s, GetBitContext *gb)
     /* unpack the C plane DC coefficients */
     residual_eob_run = unpack_vlcs(s, gb, &s->dc_vlc[dc_c_table], 0,
         1, residual_eob_run);
+    if (residual_eob_run < 0)
+        return residual_eob_run;
     residual_eob_run = unpack_vlcs(s, gb, &s->dc_vlc[dc_c_table], 0,
         2, residual_eob_run);
+    if (residual_eob_run < 0)
+        return residual_eob_run;
 
     /* reverse prediction of the C-plane DC coefficients */
     if (!(s->avctx->flags & CODEC_FLAG_GRAY))
@@ -1036,11 +1047,17 @@ static int unpack_dct_coeffs(Vp3DecodeContext *s, GetBitContext *gb)
     for (i = 1; i <= 63; i++) {
             residual_eob_run = unpack_vlcs(s, gb, y_tables[i], i,
                 0, residual_eob_run);
+            if (residual_eob_run < 0)
+                return residual_eob_run;
 
             residual_eob_run = unpack_vlcs(s, gb, c_tables[i], i,
                 1, residual_eob_run);
+            if (residual_eob_run < 0)
+                return residual_eob_run;
             residual_eob_run = unpack_vlcs(s, gb, c_tables[i], i,
                 2, residual_eob_run);
+            if (residual_eob_run < 0)
+                return residual_eob_run;
     }
 
     return 0;
@@ -1789,10 +1806,15 @@ static int vp3_update_thread_context(AVCodecContext *dst, const AVCodecContext *
     Vp3DecodeContext *s = dst->priv_data, *s1 = src->priv_data;
     int qps_changed = 0, i, err;
 
+#define copy_fields(to, from, start_field, end_field) memcpy(&to->start_field, &from->start_field, (char*)&to->end_field - (char*)&to->start_field)
+
     if (!s1->current_frame.data[0]
         ||s->width != s1->width
-        ||s->height!= s1->height)
+        ||s->height!= s1->height) {
+        if (s != s1)
+            copy_fields(s, s1, golden_frame, current_frame);
         return -1;
+    }
 
     if (s != s1) {
         // init tables if the first frame hasn't been decoded
@@ -1808,8 +1830,6 @@ static int vp3_update_thread_context(AVCodecContext *dst, const AVCodecContext *
             memcpy(s->motion_val[1], s1->motion_val[1], c_fragment_count * sizeof(*s->motion_val[1]));
         }
 
-#define copy_fields(to, from, start_field, end_field) memcpy(&to->start_field, &from->start_field, (char*)&to->end_field - (char*)&to->start_field)
-
         // copy previous frame data
         copy_fields(s, s1, golden_frame, dsp);
 
@@ -1999,9 +2019,6 @@ static av_cold int vp3_decode_end(AVCodecContext *avctx)
     Vp3DecodeContext *s = avctx->priv_data;
     int i;
 
-    if (avctx->is_copy && !s->current_frame.data[0])
-        return 0;
-
     av_free(s->superblock_coding);
     av_free(s->all_fragments);
     av_free(s->coded_fragment_list[0]);
@@ -2028,12 +2045,7 @@ static av_cold int vp3_decode_end(AVCodecContext *avctx)
     free_vlc(&s->motion_vector_vlc);
 
     /* release all frames */
-    if (s->golden_frame.data[0])
+    vp3_decode_flush(avctx);
-        ff_thread_release_buffer(avctx, &s->golden_frame);
-    if (s->last_frame.data[0] && s->last_frame.type != FF_BUFFER_TYPE_COPY)
-        ff_thread_release_buffer(avctx, &s->last_frame);
-    /* no need to release the current_frame since it will always be pointing
-     * to the same frame as either the golden or last frame */
 
     return 0;
 }
@@ -2353,6 +2365,23 @@ static void vp3_decode_flush(AVCodecContext *avctx)
         ff_thread_release_buffer(avctx, &s->current_frame);
 }
 
+static int vp3_init_thread_copy(AVCodecContext *avctx)
+{
+    Vp3DecodeContext *s = avctx->priv_data;
+
+    s->superblock_coding      = NULL;
+    s->all_fragments          = NULL;
+    s->coded_fragment_list[0] = NULL;
+    s->dct_tokens_base        = NULL;
+    s->superblock_fragments   = NULL;
+    s->macroblock_coding      = NULL;
+    s->motion_val[0]          = NULL;
+    s->motion_val[1]          = NULL;
+    s->edge_emu_buffer        = NULL;
+
+    return 0;
+}
+
 AVCodec ff_theora_decoder = {
     "theora",
     AVMEDIA_TYPE_VIDEO,
@@ -2366,6 +2395,7 @@ AVCodec ff_theora_decoder = {
     NULL,
     .flush = vp3_decode_flush,
     .long_name = NULL_IF_CONFIG_SMALL("Theora"),
+    .init_thread_copy      = ONLY_IF_THREADS_ENABLED(vp3_init_thread_copy),
     .update_thread_context = ONLY_IF_THREADS_ENABLED(vp3_update_thread_context)
 };
 #endif
@@ -2383,5 +2413,6 @@ AVCodec ff_vp3_decoder = {
     NULL,
     .flush = vp3_decode_flush,
     .long_name = NULL_IF_CONFIG_SMALL("On2 VP3"),
+    .init_thread_copy      = ONLY_IF_THREADS_ENABLED(vp3_init_thread_copy),
     .update_thread_context = ONLY_IF_THREADS_ENABLED(vp3_update_thread_context)
 };