On 5/12/17, Paul B Mahol <one...@gmail.com> wrote: > 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? >
Feel free to commit this until I came with better solution. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel