Bug#867579: libopenmpt: Security updates libopenmpt-0.2.7386-beta20.3-p10 available

[Jörn Heusipp]

Source: libopenmpt
Version: 0.2.7386~beta20.3-3
Severity: important
Tags: upstream

Dear Maintainer,


A couple of security-related fixes have been released upstream as
version 0.2.7386-beta20.3-p10. See
https://lib.openmpt.org/libopenmpt/md_announce-2017-07-07.html .

p10 fixes a heap buffer overflow which allows an attacker to write
arbitrary data to an arbitrarily choosen offset. It can be triggered
with a maliciously modified PSM file. This needs to be fixed ASAP via
a security update in Stretch. The bug happens due to 2 samples in a
PSM file using the same sample slot in libopenmpt, whereby the second
sample uses an invalid offset inside the file. That way, the second
sample did not re-allocate (via
sampleHeader.GetSampleFormat().ReadSample(Samples[smp], file); deeper
down the call chain in SampleIO.cpp:73) the sample buffer itself but
only set the sample size metadata
(sampleHeader.ConvertToMPT(Samples[smp]);, ultimately at
Load_psm.cpp:1054). Later, as a loading post-processing step,
Sndfile.cpp:411 calls PrecomputeLoops() which writes a couple of
samples before and after the actual sample data (the amount is
statically known (InterpolationMaxLookahead) and accounted for when
allocating the sample buffer). However, due to the sample buffer and
sample length mismatch caused by the bug, this can write extrapolated
sample data to an arbitary location offset from the first sample's
buffer (PrecomputeLoopsImpl<T>() in modsmp_ctrl.cpp:263).

p8 is an out-of-bounds read directly after a heap-allocated allocated
buffer. It is difficult to trigger in practice because std::vector
does grow its buffer exponentially.

p9 fixes another potential race condition due to the use of non
thread-safe <time.h> functions. As discussed previously in
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=864195#67 , this
again can at worst cause wrong data to be returned for date metadata
in libopenmpt. However, please note that the same, now rewritten code
path, could also trigger an assertion failure in glibc under memory
pressure (which probably is a glibc bug, see
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=867283 ), thereby
causing the application to crash.


-- System Information:
Debian Release: 9.0
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.9.0-3-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)