On Tue, Jan 21, 2025 at 09:57:43PM +0000, Michael Niedermayer wrote: > ffmpeg | branch: master | Michael Niedermayer <mich...@niedermayer.cc> | Thu > Dec 26 02:53:45 2024 +0100| [17b019c517af26c6d2f0c6266938c60d36db1fa3] | > committer: Michael Niedermayer > > avformat/wtvdec: Initialize buf > > ff_parse_mpeg2_descriptor() reads over what is initialized > Fixes: use of uninitialized memory > Fixes: > 383825645/clusterfuzz-testcase-minimized-ffmpeg_dem_WTV_fuzzer-5144130618982400 > > Found-by: continuous fuzzing process > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > > > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=17b019c517af26c6d2f0c6266938c60d36db1fa3 > --- > > libavformat/wtvdec.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/libavformat/wtvdec.c b/libavformat/wtvdec.c > index 730c7fca78..21c9649869 100644 > --- a/libavformat/wtvdec.c > +++ b/libavformat/wtvdec.c > @@ -833,7 +833,7 @@ static int parse_chunks(AVFormatContext *s, int mode, > int64_t seekts, int *len_p > int stream_index = ff_find_stream_index(s, sid); > if (stream_index >= 0) { > AVStream *st = s->streams[stream_index]; > - uint8_t buf[258]; > + uint8_t buf[258] = {0}; > const uint8_t *pbuf = buf;
hi michael, can you help me understand why this is needed... the avio_read() call fills buf, and the call to ff_parse_mpeg2_descriptor specifies an "end" pointer (desc_list_end point) to prevent overreading. where is the uninitialised memory coming from? -- Peter (A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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