Add support for standalone leak-sanitizer, introducting the environment

variable AFL_USE_LSAN.

AFL_USE_LSAN introduces the macro __AFL_CHECK_LEAK() which will check
for a memory leak when the macro is run. This is especially helpful
when using __AFL_LOOP().

If __AFL_LEAK_CHECK() is not used when AFL_USE_LSAN=1 is set,
the leak checker will run when the program exits.

1 files changed, 7 insertions, 0 deletions

diff --git a/docs/notes_for_asan.md b/docs/notes_for_asan.md
index 2b3bc028..26f34fad 100644
--- a/docs/notes_for_asan.md
+++ b/docs/notes_for_asan.md
@@ -28,6 +28,13 @@ Note that ASAN is incompatible with -static, so be mindful of that.
 
 (You can also use AFL_USE_MSAN=1 to enable MSAN instead.)
 
+When compiling with AFL_USE_LSAN, the leak sanitizer will normally run
+when the program exits. In order to utilize this check at different times,
+such as at the end of a loop, you may use the macro __AFL_CHECK_LEAK();.
+This macro will report a crash in afl-fuzz if any memory is left leaking
+at this stage. You can also use LSAN_OPTIONS and a supressions file
+for more fine-tuned checking, however make sure you keep exitcode=23.
+
 NOTE: if you run several secondary instances, only one should run the target
 compiled with ASAN (and UBSAN, CFISAN), the others should run the target with
 no sanitizers compiled in.