[FFmpeg-cvslog] avcodec/hnm4video: fix write offset checks in decode_interframe_v4()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Fri Nov 22 21:55:13 2013 +0100| [78446f0d9d6a57f6f58e4c0f00cc30ecff205046] | committer: Michael Niedermayer

avcodec/hnm4video: fix write offset checks in decode_interframe_v4()

Fixes: asan_heap-oob_e76a51_1244_CASSE.HNM

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=78446f0d9d6a57f6f58e4c0f00cc30ecff205046
---

 libavcodec/hnm4video.c |   15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/libavcodec/hnm4video.c b/libavcodec/hnm4video.c
index 5979926..b3cf8ef 100644
--- a/libavcodec/hnm4video.c
+++ b/libavcodec/hnm4video.c
@@ -157,7 +157,12 @@ static void decode_interframe_v4(AVCodecContext *avctx, uint8_t *src, uint32_t s
         if (count == 0) {
             tag = bytestream2_get_byte(&gb) & 0xE0;
             tag = tag >> 5;
+
             if (tag == 0) {
+                if (writeoffset + 2 > hnm->width * hnm->height) {
+                    av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
+                    break;
+                }
                 hnm->current[writeoffset++] = bytestream2_get_byte(&gb);
                 hnm->current[writeoffset++] = bytestream2_get_byte(&gb);
             } else if (tag == 1) {
@@ -168,6 +173,10 @@ static void decode_interframe_v4(AVCodecContext *avctx, uint8_t *src, uint32_t s
                 writeoffset += count;
             } else if (tag == 3) {
                 count = bytestream2_get_byte(&gb) * 2;
+                if (writeoffset + count > hnm->width * hnm->height) {
+                    av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
+                    break;
+                }
                 while (count > 0) {
                     hnm->current[writeoffset++] = bytestream2_peek_byte(&gb);
                     count--;
@@ -176,6 +185,10 @@ static void decode_interframe_v4(AVCodecContext *avctx, uint8_t *src, uint32_t s
             } else {
                 break;
             }
+            if (writeoffset > hnm->width * hnm->height) {
+                av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
+                break;
+            }
         } else {
             previous = bytestream2_peek_byte(&gb) & 0x20;
             backline = bytestream2_peek_byte(&gb) & 0x40;
@@ -194,7 +207,7 @@ static void decode_interframe_v4(AVCodecContext *avctx, uint8_t *src, uint32_t s
             } else if (backward && offset + 1 >= hnm->width * hnm->height) {
                 av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds");
                 break;
-            } else if (writeoffset + count >= hnm->width * hnm->height) {
+            } else if (writeoffset + 2*count > hnm->width * hnm->height) {
                 av_log(avctx, AV_LOG_ERROR,
                        "Attempting to write out of bounds");
                 break;