From 30666cb81eca8b36b7f95ee569ec3fd85ae616b5 Mon Sep 17 00:00:00 2001 From: intrigus-lgtm <60750685+intrigus-lgtm@users.noreply.github.com> Date: Tue, 11 Jan 2022 16:59:37 +0100 Subject: Highlight what a basic block is. Highlight the different parts that characterize what a basic block is. This makes it slightly easier to read/understand IMHO. --- docs/FAQ.md | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'docs/FAQ.md') diff --git a/docs/FAQ.md b/docs/FAQ.md index 3d3dce20..7ca7b178 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -58,10 +58,10 @@ If you find an interesting or important question missing, submit it via A program contains `functions`, `functions` contain the compiled machine code. The compiled machine code in a `function` can be in a single or many `basic - blocks`. A `basic block` is the largest possible number of subsequent machine - code instructions that has exactly one entry point (which can be be entered by - multiple other basic blocks) and runs linearly without branching or jumping to - other addresses (except at the end). + blocks`. A `basic block` is the **largest possible number of subsequent machine + code instructions** that has **exactly one entry point** (which can be be entered by + multiple other basic blocks) and runs linearly **without branching or jumping to + other addresses** (except at the end). ``` function() { @@ -225,4 +225,4 @@ If you find an interesting or important question missing, submit it via package and because of that the AFL++ llvm plugins do not match anymore. Solution: `git pull ; make clean install` of AFL++. -

\ No newline at end of file +

-- cgit 1.4.1 From 6a7f184c4e27796734a1d8408c8f8abdfc04cad5 Mon Sep 17 00:00:00 2001 From: intrigus-lgtm <60750685+intrigus-lgtm@users.noreply.github.com> Date: Tue, 11 Jan 2022 17:00:26 +0100 Subject: Fix broken `code` formatting --- docs/FAQ.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'docs/FAQ.md') diff --git a/docs/FAQ.md b/docs/FAQ.md index 7ca7b178..90cae453 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -191,7 +191,7 @@ If you find an interesting or important question missing, submit it via AFL++ comes with several power schedules, initially ported from [AFLFast](https://github.com/mboehme/aflfast) however modified to be more effective and several more modes added. - The most effective modes are '-p fast` (default) and `-p explore`. + The most effective modes are `-p fast` (default) and `-p explore`. If you fuzz with several parallel afl-fuzz instances, then it is beneficial to assign a different schedule to each instance, however the majority should -- cgit 1.4.1 From 8f7e584b82e14eced00e7bd3f8c0eaf041263e12 Mon Sep 17 00:00:00 2001 From: vanhauser-thc Date: Thu, 13 Jan 2022 12:15:19 +0100 Subject: more faq --- docs/FAQ.md | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'docs/FAQ.md') diff --git a/docs/FAQ.md b/docs/FAQ.md index 90cae453..73328d6e 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -203,6 +203,31 @@ If you find an interesting or important question missing, submit it via ## Troubleshooting +
+ FATAL: forkserver is already up but an instrumented dlopen library loaded afterwards

+ + It can happen that you see this error on startup when fuzzing a target: + + ``` + [-] FATAL: forkserver is already up, but an instrumented dlopen() library + loaded afterwards. You must AFL_PRELOAD such libraries to be able + to fuzz them or LD_PRELOAD to run outside of afl-fuzz. + To ignore this set AFL_IGNORE_PROBLEMS=1. + ``` + + As the error describes, a dlopen() call is happening in the target that is loading an instrumented library after the forkserver is already in place, + This is a problem for afl-fuzz because when the forkserver is started we must know the map size already and it can't be changed later. + + The best solution is to simply set `AFL_PRELOAD=foo.so` the libraries that + are dlopen'ed (e.g. use `strace` to see which), or to set a manual forkserver + after the final dlopen(). + + If this is not a viable option you can set `AFL_IGNORE_PROBLEMS=1` but then + the existing map will be used also for the newly loaded libraries, which + allows it to work, however the efficiency of the fuzzing will be partially + degraded. +

+
I got a weird compile error from clang.

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