openbsd-ports/graphics/ffmpeg/patches/patch-libavcodec_wavpack_c

$OpenBSD: patch-libavcodec_wavpack_c,v 1.2 2011/09/21 08:58:48 sthen Exp $

- Fixed invalid access with corrupted extra bits sub-blocks.
- Fixed invalid writes with corrupted bitstreams.
- Fixed invalid access with corrupted bitstream.

--- libavcodec/wavpack.c.orig	Mon Mar 28 19:23:17 2011
+++ libavcodec/wavpack.c	Mon Sep 12 03:06:17 2011
@@ -292,7 +292,14 @@ static int wv_get_value(WavpackFrameContext *ctx, GetB
             }
         }else{
             t = get_unary_0_33(gb);
-            if(t >= 2) t = get_bits(gb, t - 1) | (1 << (t-1));
+            if(t >= 2){
+                if(get_bits_left(gb) < t-1)
+                    goto error;
+                t = get_bits(gb, t - 1) | (1 << (t-1));
+            }else{
+                if(get_bits_left(gb) < 0)
+                    goto error;
+            }
             ctx->zeroes = t;
             if(ctx->zeroes){
                 memset(ctx->ch[0].median, 0, sizeof(ctx->ch[0].median));
@@ -303,24 +310,24 @@ static int wv_get_value(WavpackFrameContext *ctx, GetB
         }
     }
 
-    if(get_bits_count(gb) >= ctx->data_size){
-        *last = 1;
-        return 0;
-    }
-
     if(ctx->zero){
         t = 0;
         ctx->zero = 0;
     }else{
         t = get_unary_0_33(gb);
-        if(get_bits_count(gb) >= ctx->data_size){
-            *last = 1;
-            return 0;
-        }
+        if(get_bits_left(gb) < 0)
+            goto error;
         if(t == 16) {
             t2 = get_unary_0_33(gb);
-            if(t2 < 2) t += t2;
-            else t += get_bits(gb, t2 - 1) | (1 << (t2 - 1));
+            if(t2 < 2){
+                if(get_bits_left(gb) < 0)
+                    goto error;
+                t += t2;
+            }else{
+                if(get_bits_left(gb) < t2 - 1)
+                    goto error;
+                t += get_bits(gb, t2 - 1) | (1 << (t2 - 1));
+            }
         }
 
         if(ctx->one){
@@ -360,9 +367,13 @@ static int wv_get_value(WavpackFrameContext *ctx, GetB
     }
     if(!c->error_limit){
         ret = base + get_tail(gb, add);
+        if (get_bits_left(gb) <= 0)
+            goto error;
     }else{
         int mid = (base*2 + add + 1) >> 1;
         while(add > c->error_limit){
+            if(get_bits_left(gb) <= 0)
+                goto error;
             if(get_bits1(gb)){
                 add -= (mid - base);
                 base = mid;
@@ -376,6 +387,10 @@ static int wv_get_value(WavpackFrameContext *ctx, GetB
     if(ctx->hybrid_bitrate)
         c->slow_level += wp_log2(ret) - LEVEL_DECAY(c->slow_level);
     return sign ? ~ret : ret;
+
+error:
+    *last = 1;
+    return 0;
 }
 
 static inline int wv_get_value_integer(WavpackFrameContext *s, uint32_t *crc, int S)
@@ -385,7 +400,7 @@ static inline int wv_get_value_integer(WavpackFrameCon
     if(s->extra_bits){
         S <<= s->extra_bits;
 
-        if(s->got_extra_bits){
+        if(s->got_extra_bits && get_bits_left(&s->gb_extra_bits) >= s->extra_bits){
             S |= get_bits(&s->gb_extra_bits, s->extra_bits);
             *crc = *crc * 9 + (S&0xffff) * 3 + ((unsigned)S>>16);
         }
@@ -580,7 +595,10 @@ static inline int wv_unpack_stereo(WavpackFrameContext
         count++;
     }while(!last && count < s->max_samples);
 
-    s->samples_left -= count;
+    if (last)
+        s->samples_left = 0;
+    else
+        s->samples_left -= count;
     if(!s->samples_left){
         if(crc != s->CRC){
             av_log(s->avctx, AV_LOG_ERROR, "CRC error\n");
@@ -658,7 +676,10 @@ static inline int wv_unpack_mono(WavpackFrameContext *
         count++;
     }while(!last && count < s->max_samples);
 
-    s->samples_left -= count;
+    if (last)
+        s->samples_left = 0;
+    else
+        s->samples_left -= count;
     if(!s->samples_left){
         if(crc != s->CRC){
             av_log(s->avctx, AV_LOG_ERROR, "CRC error\n");
@@ -1098,6 +1119,10 @@ static int wavpack_decode_block(AVCodecContext *avctx,
             samplecount = wv_unpack_stereo(s, &s->gb, samples, AV_SAMPLE_FMT_S32);
         else
             samplecount = wv_unpack_stereo(s, &s->gb, samples, AV_SAMPLE_FMT_FLT);
+
+        if (samplecount < 0)
+            return -1;
+
         samplecount >>= 1;
     }else{
         const int channel_stride = avctx->channels;
@@ -1108,6 +1133,9 @@ static int wavpack_decode_block(AVCodecContext *avctx,
             samplecount = wv_unpack_mono(s, &s->gb, samples, AV_SAMPLE_FMT_S32);
         else
             samplecount = wv_unpack_mono(s, &s->gb, samples, AV_SAMPLE_FMT_FLT);
+
+        if (samplecount < 0)
+            return -1;
 
         if(s->stereo && avctx->sample_fmt == AV_SAMPLE_FMT_S16){
             int16_t *dst = (int16_t*)samples + 1;