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[[!meta copyright="Copyright © 2010, 2011, 2012, 2013, 2014 Free Software
Foundation, Inc."]]
[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
id="license" text="Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version 1.2 or
any later version published by the Free Software Foundation; with no Invariant
Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
is included in the section entitled [[GNU Free Documentation
License|/fdl]]."]]"""]]
In the topic of *code analysis* or *program analysis* ([[!wikipedia
Program_analysis_(computer_science) desc="Wikipedia article"]]), there is
static code analysis ([[!wikipedia Static_code_analysis desc="Wikipedia
article"]]) and dynamic program analysis ([[!wikipedia Dynamic_program_analysis
desc="Wikipedia article"]]). This topic overlaps with [[performance
analysis|performance]], [[formal_verification]], as well as general
[[debugging]].
[[!toc]]
# Bounty
There is a [[!FF_project 276]][[!tag bounty]] on some of these tasks.
# Static
* [[GCC]]'s warnings. Yes, really.
* GCC plugins can be used for additional semantic analysis. For example,
<http://lwn.net/Articles/457543/>, and search for *kernel context* in
the comments.
* Have GCC make use of [[RPC]]/[[microkernel/mach/MIG]] *in*/*out*
specifiers, and have it emit useful warnings in case these are pointing
to uninitialized data (for *in* only).
* [[!wikipedia List_of_tools_for_static_code_analysis]]
* [Engineering zero-defect software](http://esr.ibiblio.org/?p=4340), Eric
S. Raymond, 2012-05-13
* [Static Source Code Analysis Tools for C](http://spinroot.com/static/)
* [Cppcheck](http://sourceforge.net/apps/mediawiki/cppcheck/)
For example, [Debian's hurd_20110319-2
package](http://qa.debian.org/daca/cppcheck/sid/hurd_20110319-2.html)
(Samuel Thibault, 2011-08-05: *I had a look at those, some are spurious;
the realloc issues are for real*).
* Coccinelle
* <http://lwn.net/Articles/315686/>
* <http://www.google.com/search?q=coccinelle+analysis>
Has already been used for finding and fixing [[!message-id desc="double
mutex unlocking issues"
"1355701890-29227-1-git-send-email-tipecaml@gmail.com"]].
* [clang](http://www.google.com/search?q=clang+analysis)
* [Linux' sparse](https://sparse.wiki.kernel.org/)
* <http://klee.llvm.org/>
* <http://blog.llvm.org/2010/04/whats-wrong-with-this-code.html>
* [Smatch](http://smatch.sourceforge.net/)
* [Parfait](http://labs.oracle.com/projects/parfait/)
* <http://lwn.net/Articles/344003/>
* [Saturn](http://saturn.stanford.edu/)
* [Flawfinder](http://www.dwheeler.com/flawfinder/)
* [sixgill](http://sixgill.org/)
* [s-spider](http://code.google.com/p/s-spider/)
* [CIL (C Intermediate Language)](http://kerneis.github.com/cil/)
* [Frama-C](http://frama-c.com/)
<teythoon> btw, I've been looking at http://frama-c.com/ lately
<teythoon> it's a theorem prover for c/c++
<braunr> oh nice
<teythoon> I think it's most impressive, it works on the hurd (aptitude
install frama-c o_O)
<teythoon> *and it works
<braunr> "Simple things should be simple,
<braunr> complex things should be possible."
<braunr> :)
<braunr> looks great
<teythoon> even the gui is awesome, allows one to browse source code in
a very impressive way
<braunr> clear separation between value changes, dependencies, side
effects
<braunr> we could have plugins for stuff like ports
<braunr> handles concurrency oO
<nalaginrut> so you want to use Frame-C to analyze the whole Hurd code
base?
<teythoon> nalaginrut: well, frama-c looks "able" to assist in
analyzing the Hurd, yes
<teythoon> nalaginrut: but theorem proving is a manual process, one
needs to guide the prover
<teythoon> nalaginrut: b/c some stuff is not decideable
<nalaginrut> I ask this because I can imagine how to analyze Linux
since all the code is in a directory. But Hurd's codes are
distributed to many other projects
<braunr> that's not a problem
<braunr> each server can be analyzed separately
<teythoon> braunr: also, each "entry point"
<nalaginrut> alright, but sounds a big work
<teythoon> it is
<braunr> otherwise, formal verification would be widespread :)
<teythoon> that, and most tools are horrible to use, frama-c is really
an exception in this regard
* [Coverity](http://www.coverity.com/) (nonfree?)
* IRC, OFTC, #debian-hurd, 2014-02-03
<pere> btw, did you consider adding hurd and mach to <URL:
https://scan.coverity.com/ > to detect bugs automatically?
<pere> I found lots of bugs in gnash, ipmitool and sysvinit when I
started scanning those projects. :)
<teythoon> i did some static analysis work, i haven't used coverty
but free tools for that
<teythoon> i think thomas wanted to look into coverty though
<pere> quite easy to set up, but you need to download and run a
non-free tarball on the build host.
<teythoon> does that tar ball contains binary code ?
<teythoon> that'd be a show stopper for the hurd of course
<pere> did not investigate. I just put it in a contained virtual
machine.
<pere> did not want it on my laptop. :)
<pere> prefer free software here. :)
<pere> but I did not have to "accept license", at least. :)
* IRC, OFTC, #debian-hurd, 2014-02-05
<pere> ah, cool. <URL: https://scan.coverity.com/projects/1307 >
is now in place. :)
[[microkernel/mach/gnumach/projects/clean_up_the_code]],
*Code_Analysis, Coverity*.
* [Splint](http://www.splint.org/)
* IRC, freenode, #hurd, 2011-12-04
<mcsim> has anyone used splint on hurd?
<mcsim> this is tool for statically checking C programs
<mcsim> seems I made it work
## Hurd-specific Applications
* [[Port Sequence Numbers|microkernel/mach/ipc/sequence_numbering]]. If
these are used, care must be taken to update them reliably, [[!message-id
"1123688017.3905.22.camel@buko.sinrega.org"]]. This could be checked by a
static analysis tool.
* [[glibc]]'s [[glibc/critical_section]]s.
# Dynamic
* [[community/gsoc/project_ideas/Valgrind]]
* glibc's `libmcheck`
* Used by GDB, for example.
* Is not thread-safe, [[!sourceware_PR 6547]], [[!sourceware_PR 9939]],
[[!sourceware_PR 12751]], [[!stackoverflow_question 314931]].
* <http://en.wikipedia.org/wiki/Electric_Fence>
* <http://sourceforge.net/projects/duma/>
* <http://wiki.debian.org/Hardening>
* <https://wiki.ubuntu.com/CompilerFlags>
* `MALLOC_CHECK_`/`MALLOC_PERTURB_`
* IRC, freenode, #glibc, 2011-09-28
<vsrinivas> two things you can do -- there is an environment
variable (DEBUG_MALLOC_ iirc?) that can be set to 2 to make
ptmalloc (glibc's allocator) more forceful and verbose wrt error
checking
<vsrinivas> another is to grab a copy of Tor's source tree and copy
out OpenBSD's allocator (its a clearly-identifyable file in the
tree); LD_PRELOAD it or link it into your app, it is even more
aggressive about detecting memory misuse.
<vsrinivas> third, Red hat has a gdb python plugin that can
instrument glibc's heap structure. its kinda handy, might help?
<vsrinivas> MALLOC_CHECK_ was the envvar you want, sorry.
* [`MALLOC_PERTURB_`](http://udrepper.livejournal.com/11429.html)
* <http://git.fedorahosted.org/cgit/initscripts.git/diff/?id=deb0df0124fbe9b645755a0a44c7cb8044f24719>
* In context of [[!message-id
"1341350006-2499-1-git-send-email-rbraun@sceen.net"]]/the `alloca` issue
mentioned in [[gnumach_page_cache_policy]]:
IRC, freenode, #hurd, 2012-07-08:
<youpi> braunr: there's actually already an ifdef REDZONE in libthreads
It's `RED_ZONE`.
<youpi> except it seems clumsy :)
<youpi> ah, no, the libthreads code properly sets the guard, just for
grow-up stacks
* GCC, LLVM/clang: [[Address Sanitizer (asan), Memory Sanitizer (msan),
Thread Sanitizer (tasn), Undefined Behavor Sanitizer (ubsan), ...|_san]]
* [GCC plugins](http://gcc.gnu.org/wiki/plugins)
* [CTraps](https://github.com/blucia0a/CTraps-gcc)
> CTraps is a gcc plugin and runtime library that inserts calls to runtime
> library functions just before shared memory accesses in parallel/concurrent
> code.
>
> The purpose of this plugin is to expose information about when and how threads
> communicate with one another to programmers for the purpose of debugging and
> performance tuning. The overhead of the instrumentation and runtime code is
> very low -- often low enough for always-on use in production code. In a series
> of initial experiments the overhead was 0-10% in many important cases.
* Input fuzzing
Not a new topic; has been used (and papers published?) for early [[UNIX]]
tools. What about some [[RPC]] fuzzing?
* <http://caca.zoy.org/wiki/zzuf>
* <http://www.ece.cmu.edu/~koopman/ballista/>
* [Jones: system call abuse](http://lwn.net/Articles/414273/), Dave
Jones, 2010.
* [Trinity: A Linux kernel fuzz tester (and then
some)](http://www.socallinuxexpo.org/scale11x/presentations/trinity-linux-kernel-fuzz-tester-and-then-some),
Dave Jones, The Eleventh Annual Southern California Linux Expo, 2013.
* Mayhem, *an automatic bug finding system*
IRC, freenode, #hurd, 2013-06-29:
<teythoon> started reading the mayhem paper referenced here
http://lists.debian.org/debian-devel/2013/06/msg00720.html
<teythoon> that's nice work, they are doing symbolic execution of x86
binary code, that's effectively model checking with some specialized
formulas
<teythoon> (too bad the mayhem code isn't available, damn those
academic people keeping the good stuff to themselvs...)
<teythoon> (and I really think that's bad practice, how should anyone
reproduce their results? that's not how science works imho...)
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