From 6a287b739f3a8660d5e4405be1302da8b3e51e88 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Tue, 4 Mar 2008 21:58:34 +0000 Subject: Detect and prevent reading over the end of counts_*. We pass the error through a context variable as this is simpler and i think also faster, but the return value of functions could be used instead of course. The code also ensures as a side effect that the AC decoder state does not become invalid. This fixes all known crashes. And outputs nothing in case of an error instead of random noise. Originally committed as revision 12316 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/apedec.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'libavcodec') diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c index 915a2f3..0f8356d 100644 --- a/libavcodec/apedec.c +++ b/libavcodec/apedec.c @@ -156,6 +156,8 @@ typedef struct APEContext { uint8_t *data_end; ///< frame data end const uint8_t *ptr; ///< current position in frame data const uint8_t *last_ptr; ///< position where last 4608-sample block ended + + int error; } APEContext; // TODO: dsputilize @@ -382,6 +384,13 @@ static inline int range_get_symbol(APEContext * ctx, cf = range_decode_culshift(ctx, 16); + if(cf > 65492){ + symbol= cf - 65535 + 63; + range_decode_update(ctx, 1, cf); + if(cf > 65535) + ctx->error=1; + return symbol; + } /* figure out the symbol inefficiently; a binary search would be much better */ for (symbol = 0; counts[symbol + 1] <= cf; symbol++); @@ -894,11 +903,19 @@ static int ape_decode_frame(AVCodecContext * avctx, nblocks = s->samples; blockstodecode = FFMIN(BLOCKS_PER_LOOP, nblocks); + s->error=0; + if ((s->channels == 1) || (s->frameflags & APE_FRAMECODE_PSEUDO_STEREO)) ape_unpack_mono(s, blockstodecode); else ape_unpack_stereo(s, blockstodecode); + if(s->error || s->ptr > s->data_end){ + s->samples=0; + av_log(avctx, AV_LOG_ERROR, "Error decoding frame\n"); + return -1; + } + for (i = 0; i < blockstodecode; i++) { *samples++ = s->decoded0[i]; if(s->channels == 2) -- cgit v1.1