Debian Bug report logs - #539807
needlessly executable stack

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Message #5 received at submit@bugs.debian.org (full text, mbox, reply):

From: Kees Cook <kees@debian.org>

To: Debian Bugs <submit@bugs.debian.org>

Subject: needlessly executable stack

Date: Mon, 3 Aug 2009 10:53:39 -0700

[Message part 1 (text/plain, inline)]

Package: mono
Version: 2.4+dfsg-6
Severity: normal
Tags: patch, security
User: ubuntu-devel@lists.ubuntu.com
Usertags: origin-ubuntu karmic ubuntu-patch

Hello!  When running a kernel that handles non-executable memory
(PAE mode), it is preferred to have applications that do not have
an executable stack for security.  The small attached patch fixes
this for mono.

https://bugzilla.novell.com/show_bug.cgi?id=439086

Thanks,

-Kees

-- 
Kees Cook                                            @debian.org

[fix_execstack_asm.dpatch (text/plain, attachment)]

Message #10 received at 539807@bugs.debian.org (full text, mbox, reply):

From: Kees Cook <kees@debian.org>

To: 539807@bugs.debian.org

Subject: "needlessly" appears to be wrong :(

Date: Thu, 6 Aug 2009 07:59:24 -0700

Sorry, I need to recommend against my patch.  It seems to break the
debugger.  :(  I'd still like to see the exec stack issue fixed.  Forcing
exec stack for all mono apps seems... unfun.  ;)


$ echo 'class MainClass { static void Main() { System.Console.WriteLine("Hello World!"); } }' > hello.cs
$ gmcs hello.cs
$ ./hello.exe
Hello World!
$ mdb ./hello.exe
Mono Debugger
(mdb) run
Starting program: ./hello.exe
Cannot read symbol file `/usr/lib/mono/2.0/mscorlib.dll.mdb': Could not
find file "/usr/lib/mono/2.0/mscorlib.dll.mdb".
Cannot read symbol file `/home/kees/hello.exe.mdb': Could not find file
"/home/kees/hello.exe.mdb".
(mdb) Thread @1 received signal 11 at #0: 0xff87c909.
0xff87c909 push $0xff87c932
quit
The program is running. Exit anyway? (y or n) y
Thread @1 exited.
Process #1 exited.
Target exited.


A good run would be:
$ mdb ./hello.exe
Mono Debugger
(mdb) run
Starting program: ./hello.exe 
Cannot read symbol file `/usr/lib/mono/2.0/mscorlib.dll.mdb': Could not
find file "/usr/lib/mono/2.0/mscorlib.dll.mdb".
Cannot read symbol file `/home/kees/hello.exe.mdb': Could not find file
"/home/kees/hello.exe.mdb".
Thread @1 stopped at #0: 0xf79bb2d6 in <MainClass:Main ()>+0x6 at 1.
   1 IL_0000: ldstr     
(mdb) cont
Hello World!
Thread @1 exited.
(mdb) Process #1 exited.
Target exited.
quit


-- 
Kees Cook                                            @debian.org

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