kvmc: fix invalid reads

Signed-off-by: Janne Grunau <janne-libav@jannau.net>

1 files changed, 66 insertions, 16 deletions

diff --git a/libavcodec/kmvc.c b/libavcodec/kmvc.c
index 07ca19479b..6c55863e7d 100644
--- a/libavcodec/kmvc.c
+++ b/libavcodec/kmvc.c
@@ -57,17 +57,21 @@ typedef struct BitBuf {
 
 #define kmvc_init_getbits(bb, src)  bb.bits = 7; bb.bitbuf = *src++;
 
-#define kmvc_getbit(bb, src, res) {\
+#define kmvc_getbit(bb, src, src_end, res) {\
     res = 0; \
     if (bb.bitbuf & (1 << bb.bits)) res = 1; \
     bb.bits--; \
     if(bb.bits == -1) { \
+        if (src >= src_end) { \
+            av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n"); \
+            return AVERROR_INVALIDDATA; \
+        } \
         bb.bitbuf = *src++; \
         bb.bits = 7; \
     } \
 }
 
-static void kmvc_decode_intra_8x8(KmvcContext * ctx, const uint8_t * src, int w, int h)
+static int kmvc_decode_intra_8x8(KmvcContext * ctx, const uint8_t * src, int src_size, int w, int h)
 {
     BitBuf bb;
     int res, val;
@@ -75,13 +79,18 @@ static void kmvc_decode_intra_8x8(KmvcContext * ctx, const uint8_t * src, int w,
     int bx, by;
     int l0x, l1x, l0y, l1y;
     int mx, my;
+    const uint8_t *src_end = src + src_size;
 
     kmvc_init_getbits(bb, src);
 
     for (by = 0; by < h; by += 8)
         for (bx = 0; bx < w; bx += 8) {
-            kmvc_getbit(bb, src, res);
+            kmvc_getbit(bb, src, src_end, res);
             if (!res) {         // fill whole 8x8 block
+                if (src >= src_end) {
+                    av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
+                    return AVERROR_INVALIDDATA;
+                }
                 val = *src++;
                 for (i = 0; i < 64; i++)
                     BLK(ctx->cur, bx + (i & 0x7), by + (i >> 3)) = val;
@@ -89,14 +98,22 @@ static void kmvc_decode_intra_8x8(KmvcContext * ctx, const uint8_t * src, int w,
                 for (i = 0; i < 4; i++) {
                     l0x = bx + (i & 1) * 4;
                     l0y = by + (i & 2) * 2;
-                    kmvc_getbit(bb, src, res);
+                    kmvc_getbit(bb, src, src_end, res);
                     if (!res) {
-                        kmvc_getbit(bb, src, res);
+                        kmvc_getbit(bb, src, src_end, res);
                         if (!res) {     // fill whole 4x4 block
+                            if (src >= src_end) {
+                                av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
+                                return AVERROR_INVALIDDATA;
+                            }
                             val = *src++;
                             for (j = 0; j < 16; j++)
                                 BLK(ctx->cur, l0x + (j & 3), l0y + (j >> 2)) = val;
                         } else {        // copy block from already decoded place
+                            if (src >= src_end) {
+                                av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
+                                return AVERROR_INVALIDDATA;
+                            }
                             val = *src++;
                             mx = val & 0xF;
                             my = val >> 4;
@@ -108,16 +125,24 @@ static void kmvc_decode_intra_8x8(KmvcContext * ctx, const uint8_t * src, int w,
                         for (j = 0; j < 4; j++) {
                             l1x = l0x + (j & 1) * 2;
                             l1y = l0y + (j & 2);
-                            kmvc_getbit(bb, src, res);
+                            kmvc_getbit(bb, src, src_end, res);
                             if (!res) {
-                                kmvc_getbit(bb, src, res);
+                                kmvc_getbit(bb, src, src_end, res);
                                 if (!res) {     // fill whole 2x2 block
+                                    if (src >= src_end) {
+                                        av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
+                                        return AVERROR_INVALIDDATA;
+                                    }
                                     val = *src++;
                                     BLK(ctx->cur, l1x, l1y) = val;
                                     BLK(ctx->cur, l1x + 1, l1y) = val;
                                     BLK(ctx->cur, l1x, l1y + 1) = val;
                                     BLK(ctx->cur, l1x + 1, l1y + 1) = val;
                                 } else {        // copy block from already decoded place
+                                    if (src >= src_end) {
+                                        av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
+                                        return AVERROR_INVALIDDATA;
+                                    }
                                     val = *src++;
                                     mx = val & 0xF;
                                     my = val >> 4;
@@ -140,9 +165,11 @@ static void kmvc_decode_intra_8x8(KmvcContext * ctx, const uint8_t * src, int w,
                 }
             }
         }
+
+    return 0;
 }
 
-static void kmvc_decode_inter_8x8(KmvcContext * ctx, const uint8_t * src, int w, int h)
+static int kmvc_decode_inter_8x8(KmvcContext * ctx, const uint8_t * src, int src_size, int w, int h)
 {
     BitBuf bb;
     int res, val;
@@ -150,15 +177,20 @@ static void kmvc_decode_inter_8x8(KmvcContext * ctx, const uint8_t * src, int w,
     int bx, by;
     int l0x, l1x, l0y, l1y;
     int mx, my;
+    const uint8_t *src_end = src + src_size;
 
     kmvc_init_getbits(bb, src);
 
     for (by = 0; by < h; by += 8)
         for (bx = 0; bx < w; bx += 8) {
-            kmvc_getbit(bb, src, res);
+            kmvc_getbit(bb, src, src_end, res);
             if (!res) {
-                kmvc_getbit(bb, src, res);
+                kmvc_getbit(bb, src, src_end, res);
                 if (!res) {     // fill whole 8x8 block
+                    if (src >= src_end) {
+                        av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
+                        return AVERROR_INVALIDDATA;
+                    }
                     val = *src++;
                     for (i = 0; i < 64; i++)
                         BLK(ctx->cur, bx + (i & 0x7), by + (i >> 3)) = val;
@@ -171,14 +203,22 @@ static void kmvc_decode_inter_8x8(KmvcContext * ctx, const uint8_t * src, int w,
                 for (i = 0; i < 4; i++) {
                     l0x = bx + (i & 1) * 4;
                     l0y = by + (i & 2) * 2;
-                    kmvc_getbit(bb, src, res);
+                    kmvc_getbit(bb, src, src_end, res);
                     if (!res) {
-                        kmvc_getbit(bb, src, res);
+                        kmvc_getbit(bb, src, src_end, res);
                         if (!res) {     // fill whole 4x4 block
+                            if (src >= src_end) {
+                                av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
+                                return AVERROR_INVALIDDATA;
+                            }
                             val = *src++;
                             for (j = 0; j < 16; j++)
                                 BLK(ctx->cur, l0x + (j & 3), l0y + (j >> 2)) = val;
                         } else {        // copy block
+                            if (src >= src_end) {
+                                av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
+                                return AVERROR_INVALIDDATA;
+                            }
                             val = *src++;
                             mx = (val & 0xF) - 8;
                             my = (val >> 4) - 8;
@@ -190,16 +230,24 @@ static void kmvc_decode_inter_8x8(KmvcContext * ctx, const uint8_t * src, int w,
                         for (j = 0; j < 4; j++) {
                             l1x = l0x + (j & 1) * 2;
                             l1y = l0y + (j & 2);
-                            kmvc_getbit(bb, src, res);
+                            kmvc_getbit(bb, src, src_end, res);
                             if (!res) {
-                                kmvc_getbit(bb, src, res);
+                                kmvc_getbit(bb, src, src_end, res);
                                 if (!res) {     // fill whole 2x2 block
+                                    if (src >= src_end) {
+                                        av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
+                                        return AVERROR_INVALIDDATA;
+                                    }
                                     val = *src++;
                                     BLK(ctx->cur, l1x, l1y) = val;
                                     BLK(ctx->cur, l1x + 1, l1y) = val;
                                     BLK(ctx->cur, l1x, l1y + 1) = val;
                                     BLK(ctx->cur, l1x + 1, l1y + 1) = val;
                                 } else {        // copy block
+                                    if (src >= src_end) {
+                                        av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
+                                        return AVERROR_INVALIDDATA;
+                                    }
                                     val = *src++;
                                     mx = (val & 0xF) - 8;
                                     my = (val >> 4) - 8;
@@ -222,6 +270,8 @@ static void kmvc_decode_inter_8x8(KmvcContext * ctx, const uint8_t * src, int w,
                 }
             }
         }
+
+    return 0;
 }
 
 static int decode_frame(AVCodecContext * avctx, void *data, int *data_size, AVPacket *avpkt)
@@ -299,10 +349,10 @@ static int decode_frame(AVCodecContext * avctx, void *data, int *data_size, AVPa
         memcpy(ctx->cur, ctx->prev, 320 * 200);
         break;
     case 3:
-        kmvc_decode_intra_8x8(ctx, buf, avctx->width, avctx->height);
+        kmvc_decode_intra_8x8(ctx, buf, buf_size, avctx->width, avctx->height);
         break;
     case 4:
-        kmvc_decode_inter_8x8(ctx, buf, avctx->width, avctx->height);
+        kmvc_decode_inter_8x8(ctx, buf, buf_size, avctx->width, avctx->height);
         break;
     default:
         av_log(avctx, AV_LOG_ERROR, "Unknown compression method %i\n", header & KMVC_METHOD);