a div zero vul in function fetch_and_process_audio（） in libtheora 1.1.1

╭─root@linux-jiangxin in /home/jiangxin/experiment/fuzz/AFL/target/libtheora-1.1.1/examples 
╰$ gdb encoder_example
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Reading symbols from encoder_example...done.

(gdb) run ../fuzz/out/Master2/crashes/id:000000,sig:08,src:000000,op:flip1,pos:22 xxx.y4m

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/
Program received signal SIGFPE, Arithmetic exception.
fetch_and_process_audio (audio=0x83b010, audiopage=audiopage@entry=0x7fffffffda10, vo=vo@entry=0x7fffffffde10, vd=vd@entry=0x7fffffffdb20, vb=vb@entry=0x7fffffffdbb0, audioflag=audioflag@entry=0) at encoder_example.c:947
947	      int toread=4096/2/audio_ch;

(gdb) bt
#0  fetch_and_process_audio (audio=0x83b010, audiopage=audiopage@entry=0x7fffffffda10, vo=vo@entry=0x7fffffffde10, vd=vd@entry=0x7fffffffdb20, vb=vb@entry=0x7fffffffdbb0, audioflag=audioflag@entry=0) at encoder_example.c:947
#1  0x0000000000405a9b in main (argc=<optimized out>, argv=<optimized out>) at encoder_example.c:1754
(gdb) p audio_ch
$1 = 0

changed the description

mentioned in commit 525be4a0

mentioned in commit 14c5c469

mentioned in merge request !15 (merged)

Instead of trying to process audio files without any audio channels, I believe the example is better of just printing an error and exiting when encountering such bogus input. I've implemented this in !15 (merged).

mentioned in commit 82fa209f

mentioned in commit 56615e23

closed with commit 56615e23