From 2877ddddda04d5c04beaf4482acfa3151c343313 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Sat, 13 Nov 2021 18:57:59 +0100 Subject: [PATCH] avcodec/vqavideo: Use GetByteContext and check for end Fixes: out of array access Fixes: Timeout Fixes: 40481/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VQA_fuzzer-6502647583080448 Signed-off-by: Michael Niedermayer --- libavcodec/vqavideo.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/libavcodec/vqavideo.c b/libavcodec/vqavideo.c index 61f0a2c950..7c1d42bcac 100644 --- a/libavcodec/vqavideo.c +++ b/libavcodec/vqavideo.c @@ -633,7 +633,7 @@ static int vqa_decode_frame_hicolor(VqaContext *s, AVFrame *frame) int vptr_chunk = -1; int vprz_chunk = -1; - const unsigned char *stream; + GetByteContext gb_stream; while (bytestream2_get_bytes_left(&s->gb) >= 8) { chunk_type = bytestream2_get_be32u(&s->gb); @@ -717,7 +717,7 @@ static int vqa_decode_frame_hicolor(VqaContext *s, AVFrame *frame) /* now uncompress the per-row RLE of the decode buffer and draw the blocks in framebuffer */ - stream = (unsigned char*)s->decode_buffer; + bytestream2_init(&gb_stream, s->decode_buffer, s->decode_buffer_size); for (int y_pos = 0; y_pos < s->height; y_pos += s->vector_height) { int x_pos = 0; @@ -725,9 +725,14 @@ static int vqa_decode_frame_hicolor(VqaContext *s, AVFrame *frame) while (x_pos < s->width) { int vector_index = 0; int count = 0; - uint16_t code = bytestream_get_le16(&stream); + uint16_t code; int type; + if (bytestream2_get_bytes_left(&gb_stream) < 2) + return AVERROR_INVALIDDATA; + + code = bytestream2_get_le16(&gb_stream); + type = code >> 13; code &= 0x1fff; @@ -742,7 +747,7 @@ static int vqa_decode_frame_hicolor(VqaContext *s, AVFrame *frame) count = 1; } else if (type < 7) { vector_index = code; - count = *stream++; + count = bytestream2_get_byte(&gb_stream); } else { av_log(s->avctx, AV_LOG_ERROR, " unknown type in VPTR chunk (%d)\n",type); return AVERROR_INVALIDDATA; @@ -771,7 +776,7 @@ static int vqa_decode_frame_hicolor(VqaContext *s, AVFrame *frame) /* we might want to read the next block index from stream */ if ((type == 2) && count > 0) { - vector_index = bytestream_get_byte(&stream); + vector_index = bytestream2_get_byte(&gb_stream); } x_pos += 4;