From 1f024b882094b26c85e87698faa002b8713b5f88 Mon Sep 17 00:00:00 2001 From: Laurent Aimar Date: Tue, 27 Sep 2011 22:05:15 +0200 Subject: [PATCH] Check for out of bound reads in the flic decoder. Signed-off-by: Michael Niedermayer --- libavcodec/flicvideo.c | 44 ++++++++++++++++++++++++++++-------------- 1 file changed, 29 insertions(+), 15 deletions(-) diff --git a/libavcodec/flicvideo.c b/libavcodec/flicvideo.c index be1ea50f75..fa925983a9 100644 --- a/libavcodec/flicvideo.c +++ b/libavcodec/flicvideo.c @@ -131,7 +131,6 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, FlicDecodeContext *s = avctx->priv_data; int stream_ptr = 0; - int stream_ptr_after_color_chunk; int pixel_ptr; int palette_ptr; unsigned char palette_idx1; @@ -171,7 +170,11 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, pixels = s->frame.data[0]; pixel_limit = s->avctx->height * s->frame.linesize[0]; + if (buf_size < 16 || buf_size > INT_MAX - (3 * 256 + FF_INPUT_BUFFER_PADDING_SIZE)) + return AVERROR_INVALIDDATA; frame_size = AV_RL32(&buf[stream_ptr]); + if (frame_size > buf_size) + frame_size = buf_size; stream_ptr += 6; /* skip the magic number */ num_chunks = AV_RL16(&buf[stream_ptr]); stream_ptr += 10; /* skip padding */ @@ -179,13 +182,16 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, frame_size -= 16; /* iterate through the chunks */ - while ((frame_size > 0) && (num_chunks > 0)) { + while ((frame_size >= 6) && (num_chunks > 0)) { + int stream_ptr_after_chunk; chunk_size = AV_RL32(&buf[stream_ptr]); if (chunk_size > frame_size) { av_log(avctx, AV_LOG_WARNING, "Invalid chunk_size = %u > frame_size = %u\n", chunk_size, frame_size); chunk_size = frame_size; } + stream_ptr_after_chunk = stream_ptr + chunk_size; + stream_ptr += 4; chunk_type = AV_RL16(&buf[stream_ptr]); stream_ptr += 2; @@ -193,8 +199,6 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, switch (chunk_type) { case FLI_256_COLOR: case FLI_COLOR: - stream_ptr_after_color_chunk = stream_ptr + chunk_size - 6; - /* check special case: If this file is from the Magic Carpet * game and uses 6-bit colors even though it reports 256-color * chunks in a 0xAF12-type file (fli_type is set to 0xAF13 during @@ -218,6 +222,9 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, if (color_changes == 0) color_changes = 256; + if (stream_ptr + color_changes * 3 > stream_ptr_after_chunk) + break; + for (j = 0; j < color_changes; j++) { unsigned int entry; @@ -234,13 +241,6 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, s->palette[palette_ptr++] = entry; } } - - /* color chunks sometimes have weird 16-bit alignment issues; - * therefore, take the hardline approach and set the stream_ptr - * to the value calculated w.r.t. the size specified by the color - * chunk header */ - stream_ptr = stream_ptr_after_color_chunk; - break; case FLI_DELTA: @@ -248,6 +248,8 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, compressed_lines = AV_RL16(&buf[stream_ptr]); stream_ptr += 2; while (compressed_lines > 0) { + if (stream_ptr + 2 > stream_ptr_after_chunk) + break; line_packets = AV_RL16(&buf[stream_ptr]); stream_ptr += 2; if ((line_packets & 0xC000) == 0xC000) { @@ -267,6 +269,8 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, CHECK_PIXEL_PTR(0); pixel_countdown = s->avctx->width; for (i = 0; i < line_packets; i++) { + if (stream_ptr + 2 > stream_ptr_after_chunk) + break; /* account for the skip bytes */ pixel_skip = buf[stream_ptr++]; pixel_ptr += pixel_skip; @@ -283,6 +287,8 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, } } else { CHECK_PIXEL_PTR(byte_run * 2); + if (stream_ptr + byte_run * 2 > stream_ptr_after_chunk) + break; for (j = 0; j < byte_run * 2; j++, pixel_countdown--) { palette_idx1 = buf[stream_ptr++]; pixels[pixel_ptr++] = palette_idx1; @@ -309,6 +315,8 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, CHECK_PIXEL_PTR(0); pixel_countdown = s->avctx->width; line_packets = buf[stream_ptr++]; + if (stream_ptr + 2 * line_packets > stream_ptr_after_chunk) + break; if (line_packets > 0) { for (i = 0; i < line_packets; i++) { /* account for the skip bytes */ @@ -318,6 +326,8 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, byte_run = (signed char)(buf[stream_ptr++]); if (byte_run > 0) { CHECK_PIXEL_PTR(byte_run); + if (stream_ptr + byte_run > stream_ptr_after_chunk) + break; for (j = 0; j < byte_run; j++, pixel_countdown--) { palette_idx1 = buf[stream_ptr++]; pixels[pixel_ptr++] = palette_idx1; @@ -355,6 +365,8 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, stream_ptr++; pixel_countdown = s->avctx->width; while (pixel_countdown > 0) { + if (stream_ptr + 1 > stream_ptr_after_chunk) + break; byte_run = (signed char)(buf[stream_ptr++]); if (byte_run > 0) { palette_idx1 = buf[stream_ptr++]; @@ -369,6 +381,8 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, } else { /* copy bytes if byte_run < 0 */ byte_run = -byte_run; CHECK_PIXEL_PTR(byte_run); + if (stream_ptr + byte_run > stream_ptr_after_chunk) + break; for (j = 0; j < byte_run; j++) { palette_idx1 = buf[stream_ptr++]; pixels[pixel_ptr++] = palette_idx1; @@ -386,10 +400,9 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, case FLI_COPY: /* copy the chunk (uncompressed frame) */ - if (chunk_size - 6 > s->avctx->width * s->avctx->height) { + if (chunk_size - 6 != s->avctx->width * s->avctx->height) { av_log(avctx, AV_LOG_ERROR, "In chunk FLI_COPY : source data (%d bytes) " \ - "bigger than image, skipping chunk\n", chunk_size - 6); - stream_ptr += chunk_size - 6; + "has incorrect size, skipping chunk\n", chunk_size - 6); } else { for (y_ptr = 0; y_ptr < s->frame.linesize[0] * s->avctx->height; y_ptr += s->frame.linesize[0]) { @@ -402,7 +415,6 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, case FLI_MINI: /* some sort of a thumbnail? disregard this chunk... */ - stream_ptr += chunk_size - 6; break; default: @@ -410,6 +422,8 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx, break; } + stream_ptr = stream_ptr_after_chunk; + frame_size -= chunk_size; num_chunks--; }