avcodec/vlc, bitstream: Allow to use BE codes to initialize LE VLC

[ffmpeg] / libavcodec / pngdec.c

diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index d72f9bbb80a62f74b650d63b397f28e87a194a32..395b86bbe7b6ddbb91ae248528ec9d3bdafa7af9 100644 (file)
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -23,6 +23,7 @@
 
 #include "libavutil/avassert.h"
 #include "libavutil/bprint.h"
+#include "libavutil/crc.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/stereo3d.h"
@@ -983,6 +984,11 @@ static int decode_fctl_chunk(AVCodecContext *avctx, PNGDecContext *s,
         return AVERROR_INVALIDDATA;
     }
 
+    if (s->pic_state & PNG_IDAT) {
+        av_log(avctx, AV_LOG_ERROR, "fctl after IDAT\n");
+        return AVERROR_INVALIDDATA;
+    }
+
     s->last_w = s->cur_w;
     s->last_h = s->cur_h;
     s->last_x_offset = s->x_offset;
@@ -1179,6 +1185,7 @@ static int handle_p_frame_apng(AVCodecContext *avctx, PNGDecContext *s,
 static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
                                AVFrame *p, AVPacket *avpkt)
 {
+    const AVCRC *crc_tab = av_crc_get_table(AV_CRC_32_IEEE_LE);
     AVDictionary **metadatap = NULL;
     uint32_t tag, length;
     int decode_next_dat = 0;
@@ -1213,6 +1220,21 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
             ret = AVERROR_INVALIDDATA;
             goto fail;
         }
+        if (avctx->err_recognition & (AV_EF_CRCCHECK | AV_EF_IGNORE_ERR)) {
+            uint32_t crc_sig = AV_RB32(s->gb.buffer + length + 4);
+            uint32_t crc_cal = ~av_crc(crc_tab, UINT32_MAX, s->gb.buffer, length + 4);
+            if (crc_sig ^ crc_cal) {
+                av_log(avctx, AV_LOG_ERROR, "CRC mismatch in chunk");
+                if (avctx->err_recognition & AV_EF_EXPLODE) {
+                    av_log(avctx, AV_LOG_ERROR, ", quitting\n");
+                    ret = AVERROR_INVALIDDATA;
+                    goto fail;
+                }
+                av_log(avctx, AV_LOG_ERROR, ", skipping\n");
+                bytestream2_skip(&s->gb, 4); /* tag */
+                goto skip_tag;
+            }
+        }
         tag = bytestream2_get_le32(&s->gb);
         if (avctx->debug & FF_DEBUG_STARTCODE)
             av_log(avctx, AV_LOG_DEBUG, "png: tag=%s length=%u\n",
@@ -1252,7 +1274,7 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
         case MKTAG('f', 'd', 'A', 'T'):
             if (!CONFIG_APNG_DECODER || avctx->codec_id != AV_CODEC_ID_APNG)
                 goto skip_tag;
-            if (!decode_next_dat) {
+            if (!decode_next_dat || length < 4) {
                 ret = AVERROR_INVALIDDATA;
                 goto fail;
             }
@@ -1575,6 +1597,8 @@ static int decode_frame_lscr(AVCodecContext *avctx,
 
     if (avpkt->size < 2)
         return AVERROR_INVALIDDATA;
+    if (avpkt->size == 2)
+        return 0;
 
     bytestream2_init(gb, avpkt->data, avpkt->size);