Leak detection is not expected to work with python targets, disable. (#4751)

Disable leak detection in python target execution wrapper since it
is not expected to work. Also, updated the documentation for python
-only code fuzzers to not use LD_PRELOAD.

1 files changed, 6 insertions, 1 deletions

diff --git a/docs/getting-started/new-project-guide/python_lang.md b/docs/getting-started/new-project-guide/python_lang.md
index 97fe1861..5bc01d90 100644
--- a/docs/getting-started/new-project-guide/python_lang.md
+++ b/docs/getting-started/new-project-guide/python_lang.md
@@ -85,9 +85,14 @@ for fuzzer in $(find $SRC -name '*_fuzzer.py'); do
   # preloaded, so this is also done here to ensure compatibility and simplify
   # test case reproduction. Since this helper script is what OSS-Fuzz will
   # actually execute, it is also always required.
+  # NOTE: If you are fuzzing python-only code and do not have native C/C++
+  # extensions, then remove the LD_PRELOAD line below as preloading sanitizer
+  # library is not required and can lead to unexpected startup crashes.
   echo "#!/bin/sh
 # LLVMFuzzerTestOneInput for fuzzer detection.
-LD_PRELOAD=\$(dirname "\$0")/libclang_rt.asan-x86_64.so \$(dirname "\$0")/$fuzzer_package \$@" > $OUT/$fuzzer_basename
+LD_PRELOAD=\$(dirname "\$0")/libclang_rt.asan-x86_64.so \
+ASAN_OPTIONS=\$ASAN_OPTIONS:detect_leaks=0 \
+\$(dirname "\$0")/$fuzzer_package \$@" > $OUT/$fuzzer_basename
   chmod u+x $OUT/$fuzzer_basename
 done
 ```