[FFmpeg-cvslog] dfa: add some checks to ensure that decoder won't write past frame end

[Kostya Shishkov]

ffmpeg | branch: release/0.10 | Kostya Shishkov <kostya.shishkov at gmail.com> | Thu May  3 20:10:36 2012 +0200| [2281ac9ffd2819ab0c4f71ac6b6a1dffef6ba76e] | committer: Reinhard Tartler

dfa: add some checks to ensure that decoder won't write past frame end

(cherry picked from commit 8099187e897ddc90cb3902332c76fb2542dac308)

Signed-off-by: Reinhard Tartler <siretart at tauware.de>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2281ac9ffd2819ab0c4f71ac6b6a1dffef6ba76e
---

 libavcodec/dfa.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/libavcodec/dfa.c b/libavcodec/dfa.c
index f440427..12629bb 100644
--- a/libavcodec/dfa.c
+++ b/libavcodec/dfa.c
@@ -170,6 +170,8 @@ static int decode_dds1(GetByteContext *gb, uint8_t *frame, int width, int height
         } else if (bitbuf & (mask << 1)) {
             frame += bytestream2_get_le16(gb) * 2;
         } else {
+            if (frame_end - frame < width + 2)
+                return AVERROR_INVALIDDATA;
             frame[0] = frame[1] =
             frame[width] = frame[width + 1] =  bytestream2_get_byte(gb);
             frame += 2;
@@ -230,6 +232,7 @@ static int decode_wdlt(GetByteContext *gb, uint8_t *frame, int width, int height
     const uint8_t *frame_end   = frame + width * height;
     uint8_t *line_ptr;
     int count, i, v, lines, segments;
+    int y = 0;
 
     lines = bytestream2_get_le16(gb);
     if (lines > height)
@@ -240,10 +243,12 @@ static int decode_wdlt(GetByteContext *gb, uint8_t *frame, int width, int height
             return -1;
         segments = bytestream2_get_le16u(gb);
         while ((segments & 0xC000) == 0xC000) {
+            unsigned skip_lines = -(int16_t)segments;
             unsigned delta = -((int16_t)segments * width);
-            if (frame_end - frame <= delta)
+            if (frame_end - frame <= delta || y + lines + skip_lines > height)
                 return -1;
             frame    += delta;
+            y        += skip_lines;
             segments = bytestream2_get_le16(gb);
         }
         if (segments & 0x8000) {
@@ -252,6 +257,7 @@ static int decode_wdlt(GetByteContext *gb, uint8_t *frame, int width, int height
         }
         line_ptr = frame;
         frame += width;
+        y++;
         while (segments--) {
             if (frame - line_ptr <= bytestream2_peek_byte(gb))
                 return -1;