non-PIC build broken on oss-fuzz

Hi!

Looks like commit eef85229d0fe9f69d325aa0231e592f35c468afb broke
oss-fuzz builds:
https://oss-fuzz-build-logs.storage.googleapis.com/log-66ab74a7-4ece-4e14-b21b-f60527dd7244.txt

The error message is:

Step #4: /usr/bin/ld: dynamic STT_GNU_IFUNC symbol php_stripslashes' with pointer equality inext/standard/string.o' can not be used when
making an executable; recompile with -fPIE and relink with -pie
Step #4: clang-10: error: linker command failed with exit code 1 (use -v
to see invocation)
Step #4: make: *** [sapi/cli/php] Error 1
Step #4: Makefile:264: recipe for target 'sapi/cli/php' failed

I'm not sure I understand what's going on here - I suspect the non-PIC
build somehow conflicts with stripslashes optimizations, but I don't
know the details. May be specific to clan builds...

Stas Malyshev
smalyshev@gmail.com

Hi!

I suspect the problem caused by "-pie" linker flag (It requires all
object files to be build with -fPIE or -fPIC).
To quick fix this, you may add PHP configure flag "--with-pic".
Actually, this should build PHP as before the patch.

I added --with-pic, it didn't change anything, same error.

--
Stas Malyshev
smalyshev@gmail.com

Hi!

how do you add "-pie" flag?

I do not. I just compile PHP. The script used to configure and build it
is here:
https://github.com/google/oss-fuzz/blob/master/projects/php/build.sh
There are no special flags there as far as I can see. The fuzzing SAPI
lives here: https://github.com/php/php-fuzzing-sapi
The compiler used is clang. You can reproduce the build by using Docker
and these instructions:
https://google.github.io/oss-fuzz/getting-started/new-project-guide/#testing-locally

Specifically:
python infra/helper.py build_image php
python infra/helper.py build_fuzzers --sanitizer address php
or, if you want to see the details, instead of second command, use:
python infra/helper.py shell php
and then:
compile

--
Stas Malyshev
smalyshev@gmail.com

Hi!

I've just rechecked, when PHP configured with "--with-pic", libtool
generates only PIC object files and there is no difference between *.lo
to *.o files.

Sorry, you were right, --with-pic works, it was my mistake.

--
Stas Malyshev
smalyshev@gmail.com