[doc] perlhacktips: address sanitizer (asan) config doesn't work

[mauke]

Where

perlhacktips

Description

https://perldoc.perl.org/blead/perlhacktips#AddressSanitizer says:

To build perl with AddressSanitizer, your Configure invocation should look like:

sh Configure -des -Dcc=clang \
   -Accflags=-fsanitize=address -Aldflags=-fsanitize=address \
   -Alddlflags=-shared\ -fsanitize=address \
   -fsanitize-blacklist=`pwd`/asan_ignore

If you do that, you get a Configure error:

Configure: cannot read config file sanitize-blacklist=.../perl5/asan_ignore.
Usage: Configure [-dehrsEKOSV] [-f config.sh] [-D symbol] [-D symbol=value]
                 [-U symbol] [-U symbol=] [-A command:symbol...]
...

The instructions to add -fsanitize-blacklist=... to the Configure invocation were added in commit 6babf54.

[khwilliamson]

I was able to run asan just now with these options:

 + /bin/bash ./Configure -des -Uversiononly '-Dprefix=/home/khw/devel' -Dusedevel '-DDEBUGGING=none' $'-D\'optimize=-O2\'' $'-Accflags=\'-fsanitize=address\'' $'-Accflags=\'-fsanitize-address-use-after-scope\'' $'-Accflags=\'-fno-omit-frame-pointer\'' $'-Accflags=\'-fno-common\'' $'-Accflags=\'-ftrapv\'' $'-Accflags=\'-fsanitize-blacklist=/home/khw/perl/leonerd_faster_asan/asan_ignore\'' $'-Accflags=\'-fsanitize=undefined\'' $'-Accflags=\'-Wno-deprecated\'' $'-Accflags=\'-DNO_NL_LOCALE_NAME\'' $'-Dman1dir=\'none\'' $'-Dman3dir=\'none\'' $'-Aldflags=\'-fsanitize=address\'' $'-Alddlflags=\'-fsanitize=address\'' $'-Aldflags=\'-fsanitize-blacklist=/home/khw/perl/leonerd_faster_asan/asan_ignore\'' $'-Alddlflags=\'-fsanitize-blacklist=/home/khw/perl/leonerd_faster_asan/asan_ignore\'' $'-Aldflags=\'-fsanitize=undefined\'' $'-Alddlflags=\'-fsanitize=undefined\'' $'-Alddlflags=\'-shared\'' '-Dcc=clang' -Dusecbacktrace -Dusethreads
ASAN_OPTIONS=detect_leaks=false:check_initialization_order=true:detect_invalid_pointer_pairs=1:strict_string_checks=true:halt_on_error=false:exitcode=0

[jkeenan]

Where

perlhacktips

Description

https://perldoc.perl.org/blead/perlhacktips#AddressSanitizer says:

To build perl with AddressSanitizer, your Configure invocation should look like:
sh Configure -des -Dcc=clang
-Accflags=-fsanitize=address -Aldflags=-fsanitize=address
-Alddlflags=-shared\ -fsanitize=address
-fsanitize-blacklist=pwd/asan_ignore

If you do that, you get a Configure error:

Configure: cannot read config file sanitize-blacklist=.../perl5/asan_ignore.
Usage: Configure [-dehrsEKOSV] [-f config.sh] [-D symbol] [-D symbol=value]
                 [-U symbol] [-U symbol=] [-A command:symbol...]
...

./Configure error confirmed. I removed -fsanitize-blacklist=pwd/asan_ignore and ./Configure completed successfully. Of course, at some point during make my machine froze completely -- not even the slightest bit of cursor movement -- and I had to do a hard reboot. But that's what I've come to expect from ASAN. What we really need in the documentation is some guidance as to how powerful a rig you need to even think of using these configuration options. I do not expect to be able to build a perl with ASAN in my lifetime.

The instructions to add -fsanitize-blacklist=... to the Configure invocation were added in commit 6babf54.

@richardleach, that was your commit. Would you like to comment?

[jkeenan]

I was able to run asan just now with these options:

 + /bin/bash ./Configure -des -Uversiononly '-Dprefix=/home/khw/devel' -Dusedevel '-DDEBUGGING=none' $'-D\'optimize=-O2\'' $'-Accflags=\'-fsanitize=address\'' $'-Accflags=\'-fsanitize-address-use-after-scope\'' $'-Accflags=\'-fno-omit-frame-pointer\'' $'-Accflags=\'-fno-common\'' $'-Accflags=\'-ftrapv\'' $'-Accflags=\'-fsanitize-blacklist=/home/khw/perl/leonerd_faster_asan/asan_ignore\'' $'-Accflags=\'-fsanitize=undefined\'' $'-Accflags=\'-Wno-deprecated\'' $'-Accflags=\'-DNO_NL_LOCALE_NAME\'' $'-Dman1dir=\'none\'' $'-Dman3dir=\'none\'' $'-Aldflags=\'-fsanitize=address\'' $'-Alddlflags=\'-fsanitize=address\'' $'-Aldflags=\'-fsanitize-blacklist=/home/khw/perl/leonerd_faster_asan/asan_ignore\'' $'-Alddlflags=\'-fsanitize-blacklist=/home/khw/perl/leonerd_faster_asan/asan_ignore\'' $'-Aldflags=\'-fsanitize=undefined\'' $'-Alddlflags=\'-fsanitize=undefined\'' $'-Alddlflags=\'-shared\'' '-Dcc=clang' -Dusecbacktrace -Dusethreads
ASAN_OPTIONS=detect_leaks=false:check_initialization_order=true:detect_invalid_pointer_pairs=1:strict_string_checks=true:halt_on_error=false:exitcode=0

Yeah, but that's about five or six times as many configuration switches as we should ever have in our documentation. Whenever someone submits a bug ticket with that many config_args (assuming it's not the Debian /usr/bin/perl), my first response is usually to ask, "Do you still get the bug if you configure with just -des -Dusedevel? After all, the total number of combinations of Perl ./Configure options is greater than the number of atoms in the universe.

And WTF is leonerd_faster_asan? That string cannot be found anywhere in our code or documentation.

[khwilliamson]

leonerd_faster_asan is part of pwd.

Here is a stripped down version of that. Change the -Dprefix to your situation; and add other needed flags

/bin/bash ./Configure -des -Uversiononly -Dprefix=/home/khw/devel -Dusedevel -Accflags='-fsanitize=address' -Accflags='-fsanitize-address-use-after-scope' -Accflags='-fno-omit-frame-pointer' -Accflags='-fno-common' -Accflags='-ftrapv' -Accflags='-fsanitize-blacklist=`pwd`/asan_ignore' -Accflags='-fsanitize=undefined' -Accflags='-Wno-deprecated' -Aldflags='-fsanitize=address' -Alddlflags='-fsanitize=address' -Aldflags='-fsanitize-blacklist=`pwd`/asan_ignore' -Alddlflags='-fsanitize-blacklist=`pwd`/asan_ignore' -Aldflags='-fsanitize=undefined' -Alddlflags='-fsanitize=undefined' -Alddlflags='-shared' -Dcc=clang
ASAN_OPTIONS=detect_leaks=false:check_initialization_order=true:detect_invalid_pointer_pairs=1:strict_string_checks=true:halt_on_error=false:exitcode=0

The -Alddlflags='-shared' may not apply to you

[jkeenan]

leonerd_faster_asan is part of pwd.

Here is a stripped down version of that. Change the -Dprefix to your situation; and add other needed flags

/bin/bash ./Configure -des -Uversiononly -Dprefix=/home/khw/devel -Dusedevel -Accflags='-fsanitize=address' -Accflags='-fsanitize-address-use-after-scope' -Accflags='-fno-omit-frame-pointer' -Accflags='-fno-common' -Accflags='-ftrapv' -Accflags='-fsanitize-blacklist=`pwd`/asan_ignore' -Accflags='-fsanitize=undefined' -Accflags='-Wno-deprecated' -Aldflags='-fsanitize=address' -Alddlflags='-fsanitize=address' -Aldflags='-fsanitize-blacklist=`pwd`/asan_ignore' -Alddlflags='-fsanitize-blacklist=`pwd`/asan_ignore' -Aldflags='-fsanitize=undefined' -Alddlflags='-fsanitize=undefined' -Alddlflags='-shared' -Dcc=clang
ASAN_OPTIONS=detect_leaks=false:check_initialization_order=true:detect_invalid_pointer_pairs=1:strict_string_checks=true:halt_on_error=false:exitcode=0

When I copy and paste that into a text editor (gedit, in this case), the string beginning with ASAN_OPTIONS= starts on a new line. So is that a separate command, or is it somehow an argument for -D=cclang?