[FFmpeg-cvslog] mjpegdec: extend check for incompatible values of s->rgb and s->ls

[Andreas Cadhalpun]

ffmpeg | branch: release/2.8 | Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com> | Thu Dec 31 16:55:43 2015 +0100| [83c0df90b0a011fcdcec031433b1d2da97d45ae8] | committer: Michael Niedermayer

mjpegdec: extend check for incompatible values of s->rgb and s->ls

This can happen if s->ls changes from 0 to 1, but picture allocation is
skipped due to s->interlaced.

In that case ff_jpegls_decode_picture could be called even though the
s->picture_ptr frame has the wrong pixel format and thus a wrong
linesize, which results in a too small zero buffer being allocated.

This fixes an out-of-bounds read in ls_decode_line.

Reviewed-by: Michael Niedermayer <michael at niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
(cherry picked from commit 7ea2db6eafa0a8a9497aab20be2cfc8742a59072)

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=83c0df90b0a011fcdcec031433b1d2da97d45ae8
---

 libavcodec/mjpegdec.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 3f81fdf..6d674b6 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -632,7 +632,8 @@ unk_pixfmt:
         av_log(s->avctx, AV_LOG_DEBUG, "decode_sof0: error, len(%d) mismatch\n", len);
     }
 
-    if (s->rgb && !s->lossless && !s->ls) {
+    if ((s->rgb && !s->lossless && !s->ls) ||
+        (!s->rgb && s->ls && s->nb_components > 1)) {
         av_log(s->avctx, AV_LOG_ERROR, "Unsupported coding and pixel format combination\n");
         return AVERROR_PATCHWELCOME;
     }