txd: port to bytestream2 API

Protects against overreads.

Signed-off-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>

1 files changed, 24 insertions, 27 deletions

diff --git a/libavcodec/txd.c b/libavcodec/txd.c
index 734062aca6..c05cc8e248 100644
--- a/libavcodec/txd.c
+++ b/libavcodec/txd.c
@@ -24,6 +24,7 @@
 #include "libavutil/intreadwrite.h"
 #include "libavutil/imgutils.h"
 #include "avcodec.h"
+#include "bytestream.h"
 #include "s3tc.h"
 
 typedef struct TXDContext {
@@ -41,25 +42,25 @@ static av_cold int txd_init(AVCodecContext *avctx) {
 
 static int txd_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
                             AVPacket *avpkt) {
-    const uint8_t *buf = avpkt->data;
     TXDContext * const s = avctx->priv_data;
+    GetByteContext gb;
     AVFrame *picture = data;
     AVFrame * const p = &s->picture;
     unsigned int version, w, h, d3d_format, depth, stride, mipmap_count, flags;
     unsigned int y, v;
     uint8_t *ptr;
-    const uint8_t *cur = buf;
-    const uint32_t *palette = (const uint32_t *)(cur + 88);
     uint32_t *pal;
 
-    version         = AV_RL32(cur);
-    d3d_format      = AV_RL32(cur+76);
-    w               = AV_RL16(cur+80);
-    h               = AV_RL16(cur+82);
-    depth           = AV_RL8 (cur+84);
-    mipmap_count    = AV_RL8 (cur+85);
-    flags           = AV_RL8 (cur+87);
-    cur            += 92;
+    bytestream2_init(&gb, avpkt->data, avpkt->size);
+    version         = bytestream2_get_le32(&gb);
+    bytestream2_skip(&gb, 72);
+    d3d_format      = bytestream2_get_le32(&gb);
+    w               = bytestream2_get_le16(&gb);
+    h               = bytestream2_get_le16(&gb);
+    depth           = bytestream2_get_byte(&gb);
+    mipmap_count    = bytestream2_get_byte(&gb);
+    bytestream2_skip(&gb, 1);
+    flags           = bytestream2_get_byte(&gb);
 
     if (version < 8 || version > 9) {
         av_log(avctx, AV_LOG_ERROR, "texture data version %i is unsupported\n",
@@ -69,10 +70,9 @@ static int txd_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
 
     if (depth == 8) {
         avctx->pix_fmt = PIX_FMT_PAL8;
-        cur += 1024;
-    } else if (depth == 16 || depth == 32)
+    } else if (depth == 16 || depth == 32) {
         avctx->pix_fmt = PIX_FMT_RGB32;
-    else {
+    } else {
         av_log(avctx, AV_LOG_ERROR, "depth of %i is unsupported\n", depth);
         return -1;
     }
@@ -96,25 +96,26 @@ static int txd_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
 
     if (depth == 8) {
         pal = (uint32_t *) p->data[1];
-        for (y=0; y<256; y++) {
-            v = AV_RB32(palette+y);
-            pal[y] = (v>>8) + (v<<24);
+        for (y = 0; y < 256; y++) {
+            v = bytestream2_get_be32(&gb);
+            pal[y] = (v >> 8) + (v << 24);
         }
+        bytestream2_skip(&gb, 4);
         for (y=0; y<h; y++) {
-            memcpy(ptr, cur, w);
+            bytestream2_get_buffer(&gb, ptr, w);
             ptr += stride;
-            cur += w;
         }
     } else if (depth == 16) {
+        bytestream2_skip(&gb, 4);
         switch (d3d_format) {
         case 0:
             if (!(flags & 1))
                 goto unsupported;
         case FF_S3TC_DXT1:
-            ff_decode_dxt1(cur, ptr, w, h, stride);
+            ff_decode_dxt1(&gb, ptr, w, h, stride);
             break;
         case FF_S3TC_DXT3:
-            ff_decode_dxt3(cur, ptr, w, h, stride);
+            ff_decode_dxt3(&gb, ptr, w, h, stride);
             break;
         default:
             goto unsupported;
@@ -124,9 +125,8 @@ static int txd_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
         case 0x15:
         case 0x16:
             for (y=0; y<h; y++) {
-                memcpy(ptr, cur, w*4);
+                bytestream2_get_buffer(&gb, ptr, w * 4);
                 ptr += stride;
-                cur += w*4;
             }
             break;
         default:
@@ -134,13 +134,10 @@ static int txd_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
         }
     }
 
-    for (; mipmap_count > 1; mipmap_count--)
-        cur += AV_RL32(cur) + 4;
-
     *picture   = s->picture;
     *data_size = sizeof(AVPicture);
 
-    return cur - buf;
+    return avpkt->size;
 
 unsupported:
     av_log(avctx, AV_LOG_ERROR, "unsupported d3d format (%08x)\n", d3d_format);