On Thu, Feb 23, 2017 at 05:53:27PM +0100, wm4 wrote: > On Thu, 23 Feb 2017 17:12:35 +0100 > Michael Niedermayer <mich...@niedermayer.cc> wrote: > > > On Thu, Feb 23, 2017 at 03:26:22PM +0100, wm4 wrote: > > > On Thu, 23 Feb 2017 15:19:31 +0100 > > > Michael Niedermayer <mich...@niedermayer.cc> wrote: > > > > > > > The size 0 special case causes side data to be created which is > > > > different and a special case if for any reasons size = 0 is passed > > > > > > > > Fixes: multiple runtime error: null pointer passed as argument 1, which > > > > is declared to never be null > > > > Fixes: 653/clusterfuzz-testcase-5773837415219200 > > > > > > > > Found-by: continuous fuzzing process > > > > https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg > > > > > > > > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > > > > --- > > > > libavutil/frame.c | 55 > > > > +++++++++++++++++++++++++++++-------------------------- > > > > 1 file changed, 29 insertions(+), 26 deletions(-) > > > > > > > > diff --git a/libavutil/frame.c b/libavutil/frame.c > > > > index 2913982e91..8811dcdcfe 100644 > > > > --- a/libavutil/frame.c > > > > +++ b/libavutil/frame.c > > > > @@ -26,6 +26,11 @@ > > > > #include "mem.h" > > > > #include "samplefmt.h" > > > > > > > > + > > > > +static AVFrameSideData *frame_new_side_data(AVFrame *frame, > > > > + enum AVFrameSideDataType > > > > type, > > > > + AVBufferRef *buf); > > > > + > > > > MAKE_ACCESSORS(AVFrame, frame, int64_t, best_effort_timestamp) > > > > MAKE_ACCESSORS(AVFrame, frame, int64_t, pkt_duration) > > > > MAKE_ACCESSORS(AVFrame, frame, int64_t, pkt_pos) > > > > @@ -344,20 +349,11 @@ FF_ENABLE_DEPRECATION_WARNINGS > > > > } > > > > memcpy(sd_dst->data, sd_src->data, sd_src->size); > > > > } else { > > > > - sd_dst = av_frame_new_side_data(dst, sd_src->type, 0); > > > > + sd_dst = frame_new_side_data(dst, sd_src->type, > > > > av_buffer_ref(sd_src->buf)); > > > > if (!sd_dst) { > > > > wipe_side_data(dst); > > > > return AVERROR(ENOMEM); > > > > } > > > > - if (sd_src->buf) { > > > > - sd_dst->buf = av_buffer_ref(sd_src->buf); > > > > - if (!sd_dst->buf) { > > > > - wipe_side_data(dst); > > > > - return AVERROR(ENOMEM); > > > > - } > > > > - sd_dst->data = sd_dst->buf->data; > > > > - sd_dst->size = sd_dst->buf->size; > > > > - } > > > > } > > > > av_dict_copy(&sd_dst->metadata, sd_src->metadata, 0); > > > > } > > > > @@ -633,40 +629,47 @@ AVBufferRef *av_frame_get_plane_buffer(AVFrame > > > > *frame, int plane) > > > > return NULL; > > > > } > > > > > > > > -AVFrameSideData *av_frame_new_side_data(AVFrame *frame, > > > > - enum AVFrameSideDataType type, > > > > - int size) > > > > +static AVFrameSideData *frame_new_side_data(AVFrame *frame, > > > > + enum AVFrameSideDataType > > > > type, > > > > + AVBufferRef *buf) > > > > { > > > > AVFrameSideData *ret, **tmp; > > > > > > > > - if (frame->nb_side_data > INT_MAX / sizeof(*frame->side_data) - 1) > > > > + if (!buf) > > > > return NULL; > > > > > > > > + if (frame->nb_side_data > INT_MAX / sizeof(*frame->side_data) - 1) > > > > + goto fail; > > > > + > > > > tmp = av_realloc(frame->side_data, > > > > (frame->nb_side_data + 1) * > > > > sizeof(*frame->side_data)); > > > > if (!tmp) > > > > - return NULL; > > > > + goto fail; > > > > frame->side_data = tmp; > > > > > > > > ret = av_mallocz(sizeof(*ret)); > > > > if (!ret) > > > > - return NULL; > > > > - > > > > - if (size > 0) { > > > > - ret->buf = av_buffer_alloc(size); > > > > - if (!ret->buf) { > > > > - av_freep(&ret); > > > > - return NULL; > > > > - } > > > > + goto fail; > > > > > > > > - ret->data = ret->buf->data; > > > > - ret->size = size; > > > > - } > > > > + ret->buf = buf; > > > > + ret->data = ret->buf->data; > > > > + ret->size = buf->size; > > > > ret->type = type; > > > > > > > > frame->side_data[frame->nb_side_data++] = ret; > > > > > > > > return ret; > > > > +fail: > > > > + av_buffer_unref(&buf); > > > > + return NULL; > > > > +} > > > > + > > > > +AVFrameSideData *av_frame_new_side_data(AVFrame *frame, > > > > + enum AVFrameSideDataType type, > > > > + int size) > > > > +{ > > > > + > > > > + return frame_new_side_data(frame, type, av_buffer_alloc(size)); > > > > } > > > > > > > > AVFrameSideData *av_frame_get_side_data(const AVFrame *frame, > > > > > > Why not restore Libav's version, which doesn't seem to need all this? > > > > it would remove optimizations and who knows what else. Also iam > > interrested in fixing security and undefined behavor issues in FFmpeg. > > The code in FFmpeg has been extensivly tested within FFmpeg and > > simply throwing it out and replacing it by something else would > > bring us to code that has not been tested in FFmpeg. > > Actually it looks like the Libav version doesn't even have this > per side-data buffer ref, which makes it so different. > > I'm not sure what's the actual problem here. If size==0, then data can > be NULL just fine? If something accesses data anyway (even if size==0), > that should probably be fixed instead.
The problem is that functions like memcpy dont allow NULL even with a size of 0 i can add checks for every memcpy() and any other function that ubsan finds if thats preferred or add a av_memcpy() that does allow NULL eliminating the 0 case seemed better to me > > In general it feels like the change makes the new code slightly > trickier than necessary (and the forward declaration looks ugly), but > feel free to ignore me. i intended to remove the forward declaration in a seperate change moving the function. I did it with a forw declare in the patch so the diff shows the differences of the function clearer [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Good people do not need laws to tell them to act responsibly, while bad people will find a way around the laws. -- Plato
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