[FFmpeg-cvslog] avcodec/mjpegdec: check that index is not negative

[Paul B Mahol]

ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Sun Sep 25 19:17:25 2022 +0200| [4f022e67822c286e0974fe27191186d80342feb1] | committer: Paul B Mahol

avcodec/mjpegdec: check that index is not negative

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=4f022e67822c286e0974fe27191186d80342feb1
---

 libavcodec/mjpegdec.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index c594950500..559bda5e6f 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -373,7 +373,10 @@ int ff_mjpeg_decode_sof(MJpegDecodeContext *s)
     s->v_max         = 1;
     for (i = 0; i < nb_components; i++) {
         /* component id */
-        s->component_id[i] = get_bits(&s->gb, 8) - 1;
+        int id = get_bits(&s->gb, 8);
+        if (id == 0)
+            return AVERROR_INVALIDDATA;
+        s->component_id[i] = id - 1;
         h_count[i]         = get_bits(&s->gb, 4);
         v_count[i]         = get_bits(&s->gb, 4);
         /* compute hmax and vmax (only used in interleaved case) */
@@ -1677,7 +1680,10 @@ int ff_mjpeg_decode_sos(MJpegDecodeContext *s, const uint8_t *mb_bitmask,
         return AVERROR_INVALIDDATA;
     }
     for (i = 0; i < nb_components; i++) {
-        id = get_bits(&s->gb, 8) - 1;
+        id = get_bits(&s->gb, 8);
+        if (id == 0)
+            return AVERROR_INVALIDDATA;
+        id -= 1;
         av_log(s->avctx, AV_LOG_DEBUG, "component: %d\n", id);
         /* find component index */
         for (index = 0; index < s->nb_components; index++)