Bug#772981: libvorbis: Suspicion of SIGFPE with corrupt input file

[Martin Steghöfer]

Package: libvorbis
Version: 1.3.4-2
Severity: normal


While investigating the cause for #772978, the relevant libvorbis code 
gave me the impression that (with input files different from the 
referenced one) the division by zero may happen even if oggdec handled 
the reported errors correctly.

The relevant stacktrace:

Process terminating with default action of
     signal 8 (SIGFPE)
  Integer divide by zero at address 0x802FA8133
    at 0x50632A6: res2_inverse (res0.c:830)
    by 0x50654A8: mapping0_inverse (mapping0.c:756)
    by 0x5054071: vorbis_synthesis (synthesis.c:88)
    by 0x4E3AC66: _fetch_and_process_packet
                  (vorbisfile.c:707)
    by 0x4E3E073: ov_read_filter (vorbisfile.c:1971)
    by 0x4E3E6D2: ov_read (vorbisfile.c:2092)
    by 0x40212A: decode_file (oggdec.c:304)
    by 0x402692: main (oggdec.c:455)

I am going to look for other ways (not exploiting oggdec's poor error 
handling) to trigger this division by zero and report it back here.

Cheers,
Martin