On 5/12/17, Michael Niedermayer <mich...@niedermayer.cc> wrote: > 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.
In theory and/or practice? _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
