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>

libavcodec/s3tc.c

@@ -21,19 +21,19 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#include "libavutil/intreadwrite.h"
+#include "libavcodec/bytestream.h"
 #include "avcodec.h"
 #include "s3tc.h"
 
-static inline void dxt1_decode_pixels(const uint8_t *s, uint32_t *d,
+static inline void dxt1_decode_pixels(GetByteContext *gb, uint32_t *d,
                                       unsigned int qstride, unsigned int flag,
                                       uint64_t alpha) {
     unsigned int x, y, c0, c1, a = (!flag * 255u) << 24;
     unsigned int rb0, rb1, rb2, rb3, g0, g1, g2, g3;
     uint32_t colors[4], pixels;
 
-    c0 = AV_RL16(s);
-    c1 = AV_RL16(s+2);
+    c0 = bytestream2_get_le16(gb);
+    c1 = bytestream2_get_le16(gb);
 
     rb0  = (c0<<3 | c0<<8) & 0xf800f8;
     rb1  = (c1<<3 | c1<<8) & 0xf800f8;
@@ -61,7 +61,7 @@ static inline void dxt1_decode_pixels(const uint8_t *s, uint32_t *d,
 
     colors[2] = rb2 + g2 + a;
 
-    pixels = AV_RL32(s+4);
+    pixels = bytestream2_get_le32(gb);
     for (y=0; y<4; y++) {
         for (x=0; x<4; x++) {
             a        = (alpha & 0x0f) << 28;
@@ -74,24 +74,24 @@ static inline void dxt1_decode_pixels(const uint8_t *s, uint32_t *d,
     }
 }
 
-void ff_decode_dxt1(const uint8_t *s, uint8_t *dst,
+void ff_decode_dxt1(GetByteContext *gb, uint8_t *dst,
                     const unsigned int w, const unsigned int h,
                     const unsigned int stride) {
     unsigned int bx, by, qstride = stride/4;
     uint32_t *d = (uint32_t *) dst;
 
     for (by=0; by < h/4; by++, d += stride-w)
-        for (bx=0; bx < w/4; bx++, s+=8, d+=4)
-            dxt1_decode_pixels(s, d, qstride, 0, 0LL);
+        for (bx = 0; bx < w / 4; bx++, d += 4)
+            dxt1_decode_pixels(gb, d, qstride, 0, 0LL);
 }
 
-void ff_decode_dxt3(const uint8_t *s, uint8_t *dst,
+void ff_decode_dxt3(GetByteContext *gb, uint8_t *dst,
                     const unsigned int w, const unsigned int h,
                     const unsigned int stride) {
     unsigned int bx, by, qstride = stride/4;
     uint32_t *d = (uint32_t *) dst;
 
     for (by=0; by < h/4; by++, d += stride-w)
-        for (bx=0; bx < w/4; bx++, s+=16, d+=4)
-            dxt1_decode_pixels(s+8, d, qstride, 1, AV_RL64(s));
+        for (bx = 0; bx < w / 4; bx++, d += 4)
+            dxt1_decode_pixels(gb, d, qstride, 1, bytestream2_get_le64(gb));
 }

libavcodec/s3tc.h

@@ -29,24 +29,24 @@
 
 /**
  * Decode DXT1 encoded data to RGB32
- * @param src source buffer, has to be aligned on a 4-byte boundary
+ * @param gb GetByteContext
  * @param dst destination buffer
  * @param w width of output image
  * @param h height of output image
  * @param stride line size of output image
  */
-void ff_decode_dxt1(const uint8_t *src, uint8_t *dst,
+void ff_decode_dxt1(GetByteContext *gb, uint8_t *dst,
                     const unsigned int w, const unsigned int h,
                     const unsigned int stride);
 /**
  * Decode DXT3 encoded data to RGB32
- * @param src source buffer, has to be aligned on a 4-byte boundary
+ * @param gb GetByteContext
  * @param dst destination buffer
  * @param w width of output image
  * @param h height of output image
  * @param stride line size of output image
  */
-void ff_decode_dxt3(const uint8_t *src, uint8_t *dst,
+void ff_decode_dxt3(GetByteContext *gb, uint8_t *dst,
                     const unsigned int w, const unsigned int h,
                     const unsigned int stride);
 

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);