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Diffstat (limited to 'utils/libdislocator/README.md')
| -rw-r--r-- | utils/libdislocator/README.md | 37 |
1 files changed, 18 insertions, 19 deletions
diff --git a/utils/libdislocator/README.md b/utils/libdislocator/README.md index d0340af0..7150c205 100644 --- a/utils/libdislocator/README.md +++ b/utils/libdislocator/README.md @@ -10,8 +10,8 @@ heap-related security bugs in several ways: subsequent PROT_NONE page, causing most off-by-one reads and writes to immediately segfault, - - It adds a canary immediately below the allocated buffer, to catch writes - to negative offsets (won't catch reads, though), + - It adds a canary immediately below the allocated buffer, to catch writes to + negative offsets (won't catch reads, though), - It sets the memory returned by malloc() to garbage values, improving the odds of crashing when the target accesses uninitialized data, @@ -19,37 +19,36 @@ heap-related security bugs in several ways: - It sets freed memory to PROT_NONE and does not actually reuse it, causing most use-after-free bugs to segfault right away, - - It forces all realloc() calls to return a new address - and sets - PROT_NONE on the original block. This catches use-after-realloc bugs, + - It forces all realloc() calls to return a new address - and sets PROT_NONE + on the original block. This catches use-after-realloc bugs, - - It checks for calloc() overflows and can cause soft or hard failures - of alloc requests past a configurable memory limit (AFL_LD_LIMIT_MB, + - It checks for calloc() overflows and can cause soft or hard failures of + alloc requests past a configurable memory limit (AFL_LD_LIMIT_MB, AFL_LD_HARD_FAIL). - Optionally, in platforms supporting it, huge pages can be used by passing USEHUGEPAGE=1 to make. - - - Size alignment to `max_align_t` can be enforced with AFL_ALIGNED_ALLOC=1. - In this case, a tail canary is inserted in the padding bytes at the end - of the allocated zone. This reduce the ability of libdislocator to detect + + - Size alignment to `max_align_t` can be enforced with AFL_ALIGNED_ALLOC=1. In + this case, a tail canary is inserted in the padding bytes at the end of the + allocated zone. This reduce the ability of libdislocator to detect off-by-one bugs but also it make slibdislocator compliant to the C standard. Basically, it is inspired by some of the non-default options available for the OpenBSD allocator - see malloc.conf(5) on that platform for reference. It is -also somewhat similar to several other debugging libraries, such as gmalloc -and DUMA - but is simple, plug-and-play, and designed specifically for fuzzing -jobs. +also somewhat similar to several other debugging libraries, such as gmalloc and +DUMA - but is simple, plug-and-play, and designed specifically for fuzzing jobs. Note that it does nothing for stack-based memory handling errors. The -fstack-protector-all setting for GCC / clang, enabled when using AFL_HARDEN, can catch some subset of that. The allocator is slow and memory-intensive (even the tiniest allocation uses up -4 kB of physical memory and 8 kB of virtual mem), making it completely unsuitable -for "production" uses; but it can be faster and more hassle-free than ASAN / MSAN -when fuzzing small, self-contained binaries. +4 kB of physical memory and 8 kB of virtual mem), making it completely +unsuitable for "production" uses; but it can be faster and more hassle-free than +ASAN / MSAN when fuzzing small, self-contained binaries. -To use this library, run AFL like so: +To use this library, run AFL++ like so: ``` AFL_PRELOAD=/path/to/libdislocator.so ./afl-fuzz [...other params...] @@ -62,7 +61,7 @@ Similarly to afl-tmin, the library is not "proprietary" and can be used with other fuzzers or testing tools without the need for any code tweaks. It does not require AFL-instrumented binaries to work. -Note that the AFL_PRELOAD approach (which AFL internally maps to LD_PRELOAD or +Note that the AFL_PRELOAD approach (which AFL++ internally maps to LD_PRELOAD or DYLD_INSERT_LIBRARIES, depending on the OS) works only if the target binary is dynamically linked. Otherwise, attempting to use the library will have no -effect. +effect. \ No newline at end of file |