On Sun, Sep 04, 2016 at 08:58:44PM +0200, Carl Eugen Hoyos wrote: > Hi! > > Some scanner - scannersoftware combination (HP_Officejet_Pro_X476dn_MFP > - sane) truncates trailing zeros in pbm files and FreeImage (a library > used in free and proprietary image software) reads such files. > Attached patch copies this behaviour and fixes ticket #5795. > > Please comment, Carl Eugen
> pnmdec.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
> fd31d6d029cade2e5eb2f2a705067cdaa2ab02d5
> 0001-lavc-pnmdec-Do-not-abort-by-default-for-truncated-pb.patch
> From af00c56b38b28e07bbba46031472da41300a8cf1 Mon Sep 17 00:00:00 2001
> From: Carl Eugen Hoyos <ceho...@ag.or.at>
> Date: Sun, 4 Sep 2016 20:52:28 +0200
> Subject: [PATCH] lavc/pnmdec: Do not abort by default for truncated pbm
> files.
>
> Fixes ticket #5795.
> ---
> libavcodec/pnmdec.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/libavcodec/pnmdec.c b/libavcodec/pnmdec.c
> index d4261a4..0b7a0f6 100644
> --- a/libavcodec/pnmdec.c
> +++ b/libavcodec/pnmdec.c
> @@ -124,8 +124,12 @@ static int pnm_decode_frame(AVCodecContext *avctx, void
> *data,
> do_read:
> ptr = p->data[0];
> linesize = p->linesize[0];
> - if (s->bytestream + n * avctx->height > s->bytestream_end)
> - return AVERROR_INVALIDDATA;
> + if (s->bytestream + n * avctx->height > s->bytestream_end) {
> + av_log(avctx, AV_LOG_ERROR,
> + "Invalid truncated file\n");
> + if (avctx->strict_std_compliance >= FF_COMPLIANCE_STRICT)
> + return AVERROR_INVALIDDATA;
> + }
> if(s->type < 4 || (is_mono && s->type==7)){
> for (i=0; i<avctx->height; i++) {
> PutBitContext pb;
> @@ -159,6 +163,8 @@ static int pnm_decode_frame(AVCodecContext *avctx, void
> *data,
> }
> }else{
> for (i = 0; i < avctx->height; i++) {
> + if (s->bytestream + n > s->bytestream_end)
> + continue;
having a pointer point outside of 0..array length is undefined
behaviour (and can overflow in principle)
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety -- Benjamin Franklin
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