On Fri, May 12, 2017 at 03:29:52PM +0200, Paul B Mahol wrote: > On 5/12/17, Michael Niedermayer <mich...@niedermayer.cc> wrote: > > On Thu, May 11, 2017 at 11:17:33AM +0200, Michael Niedermayer wrote: > >> On Thu, May 11, 2017 at 09:01:57AM +0200, Paul B Mahol wrote: > >> > On 5/11/17, Michael Niedermayer <mich...@niedermayer.cc> wrote: > >> > > Most of these were found through code review in response to > >> > > fixing 1466/clusterfuzz-testcase-minimized-5961584419536896 > >> > > There is thus no testcase for most of this. > >> > > The initial issue was Found-by: continuous fuzzing process > >> > > https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg > >> > > > >> > > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > >> > > --- > >> > > libavcodec/xpmdec.c | 37 ++++++++++++++++++++++++++++++------- > >> > > 1 file changed, 30 insertions(+), 7 deletions(-) > >> > > > >> > > diff --git a/libavcodec/xpmdec.c b/libavcodec/xpmdec.c > >> > > index 9112d4cb5e..03172e4aad 100644 > >> > > --- a/libavcodec/xpmdec.c > >> > > +++ b/libavcodec/xpmdec.c > >> > > @@ -29,6 +29,8 @@ > >> > > typedef struct XPMContext { > >> > > uint32_t *pixels; > >> > > int pixels_size; > >> > > + uint8_t *buf; > >> > > + int buf_size; > >> > > } XPMDecContext; > >> > > > >> > > typedef struct ColorEntry { > >> > > @@ -233,6 +235,8 @@ static uint32_t color_string_to_rgba(const char > >> > > *p, int > >> > > len) > >> > > const ColorEntry *entry; > >> > > char color_name[100]; > >> > > > >> > > + len = FFMIN(FFMAX(len, 0), sizeof(color_name) - 1); > >> > > + > >> > > if (*p == '#') { > >> > > p++; > >> > > len--; > >> > > @@ -299,18 +303,25 @@ static int xpm_decode_frame(AVCodecContext > >> > > *avctx, > >> > > void *data, > >> > > { > >> > > XPMDecContext *x = avctx->priv_data; > >> > > AVFrame *p=data; > >> > > - const uint8_t *end, *ptr = avpkt->data; > >> > > + const uint8_t *end, *ptr; > >> > > int ncolors, cpp, ret, i, j; > >> > > int64_t size; > >> > > uint32_t *dst; > >> > > > >> > > avctx->pix_fmt = AV_PIX_FMT_BGRA; > >> > > > >> > > - end = avpkt->data + avpkt->size; > >> > > - while (memcmp(ptr, "/* XPM */", 9) && ptr < end - 9) > >> > > + av_fast_padded_malloc(&x->buf, &x->buf_size, avpkt->size); > >> > > + if (!x->buf) > >> > > + return AVERROR(ENOMEM); > >> > > + memcpy(x->buf, avpkt->data, avpkt->size); > >> > > + x->buf[avpkt->size] = 0; > >> > > + > >> > > + ptr = x->buf; > >> > > + end = x->buf + avpkt->size; > >> > > + while (end - ptr > 9 && memcmp(ptr, "/* XPM */", 9)) > >> > > ptr++; > >> > > > >> > > - if (ptr >= end) { > >> > > + if (end - ptr <= 9) { > >> > > av_log(avctx, AV_LOG_ERROR, "missing signature\n"); > >> > > return AVERROR_INVALIDDATA; > >> > > } > >> > > @@ -335,7 +346,7 @@ static int xpm_decode_frame(AVCodecContext *avctx, > >> > > void > >> > > *data, > >> > > > >> > > size = 1; > >> > > for (i = 0; i < cpp; i++) > >> > > - size *= 94; > >> > > + size *= 95; > >> > > > >> > > if (ncolors <= 0 || ncolors > size) { > >> > > av_log(avctx, AV_LOG_ERROR, "invalid number of colors: > >> > > %d\n", > >> > > ncolors); > >> > > @@ -349,12 +360,15 @@ static int xpm_decode_frame(AVCodecContext > >> > > *avctx, > >> > > void *data, > >> > > return AVERROR(ENOMEM); > >> > > > >> > > ptr += mod_strcspn(ptr, ",") + 1; > >> > > + if (end - ptr < 1) > >> > > + return AVERROR_INVALIDDATA; > >> > > + > >> > > for (i = 0; i < ncolors; i++) { > >> > > const uint8_t *index; > >> > > int len; > >> > > > >> > > ptr += mod_strcspn(ptr, "\"") + 1; > >> > > - if (ptr + cpp > end) > >> > > + if (end - ptr < cpp) > >> > > return AVERROR_INVALIDDATA; > >> > > index = ptr; > >> > > ptr += cpp; > >> > > @@ -373,14 +387,20 @@ static int xpm_decode_frame(AVCodecContext > >> > > *avctx, > >> > > void *data, > >> > > > >> > > x->pixels[ret] = color_string_to_rgba(ptr, len); > >> > > ptr += mod_strcspn(ptr, ",") + 1; > >> > > + if (end - ptr < 1) > >> > > + return AVERROR_INVALIDDATA; > >> > > } > >> > > > >> > > for (i = 0; i < avctx->height; i++) { > >> > > dst = (uint32_t *)(p->data[0] + i * p->linesize[0]); > >> > > + if (end - ptr < 1) > >> > > + return AVERROR_INVALIDDATA; > >> > > ptr += mod_strcspn(ptr, "\"") + 1; > >> > > + if (end - ptr < 1) > >> > > + return AVERROR_INVALIDDATA; > >> > > > >> > > for (j = 0; j < avctx->width; j++) { > >> > > - if (ptr + cpp > end) > >> > > + if (end - ptr < cpp) > >> > > return AVERROR_INVALIDDATA; > >> > > > >> > > if ((ret = ascii2index(ptr, cpp)) < 0) > >> > > @@ -405,6 +425,9 @@ static av_cold int > >> > > xpm_decode_close(AVCodecContext > >> > > *avctx) > >> > > XPMDecContext *x = avctx->priv_data; > >> > > av_freep(&x->pixels); > >> > > > >> > > + av_freep(&x->buf); > >> > > + x->buf_size = 0; > >> > > + > >> > > return 0; > >> > > } > >> > > > >> > > -- > >> > > 2.11.0 > >> > > > >> > > _______________________________________________ > >> > > ffmpeg-devel mailing list > >> > > ffmpeg-devel@ffmpeg.org > >> > > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > >> > > > >> > > >> > This is suboptimal solution. > >> > >> That comment isnt helpfull in improving the patch. It doesnt say > >> what it is that you would like changed. > >> > >> I could probably replace string functions and avoid copying the whole > >> packet if thats what you suggest ? > >> it makes this bugfix more complex though > > > > ping, this is a security issue and needs to be fixed > > > I told you that its unacceptable. >
> Do this: avpkt->data[avpkt->size] = 0; packet input to a decoder is not writable, in fact it could be part of a memory maped file and litterally be in non writable memory. [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Democracy is the form of government in which you can choose your dictator
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