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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 20:45:25 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 20:45:25 +0000 |
commit | 814d128d1c52fe82be73ecff5b7472378041313f (patch) | |
tree | 581db0c07936d6d608e8c2e72d4903df306dd589 /fuzz/README | |
parent | Initial commit. (diff) | |
download | libfido2-814d128d1c52fe82be73ecff5b7472378041313f.tar.xz libfido2-814d128d1c52fe82be73ecff5b7472378041313f.zip |
Adding upstream version 1.14.0.upstream/1.14.0
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fuzz/README')
-rw-r--r-- | fuzz/README | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/fuzz/README b/fuzz/README new file mode 100644 index 0000000..427625c --- /dev/null +++ b/fuzz/README @@ -0,0 +1,43 @@ +libfido2 can be fuzzed using AFL or libFuzzer, with or without +ASAN/MSAN/UBSAN. + +AFL is more convenient when fuzzing the path from the authenticator to +libfido2 in an existing application. To do so, use preload-snoop.c with a real +authenticator to obtain an initial corpus, rebuild libfido2 with -DFUZZ=ON, and +use preload-fuzz.c to read device data from stdin. + +libFuzzer is better suited for bespoke fuzzers; see fuzz_cred.c, fuzz_credman.c, +fuzz_assert.c, fuzz_hid.c, and fuzz_mgmt.c for examples. To build these +harnesses, use -DCMAKE_C_FLAGS=-fsanitize=fuzzer-no-link +-DFUZZ_LDFLAGS=-fsanitize=fuzzer -DFUZZ=ON. + +If -DFUZZ=ON is enabled, symbols listed in wrapped.sym are wrapped in the +resulting shared object. The wrapper functions simulate failure according to a +deterministic RNG and probabilities defined in wrap.c. Harnesses wishing to +use this functionality should call prng_init() with a seed obtained from the +corpus. To mutate only the seed part of a libFuzzer harness's corpora, +use '-reduce_inputs=0 --fido-mutate=seed'. + +To run under ASAN/MSAN/UBSAN, libfido2 needs to be linked against flavours of +libcbor and OpenSSL built with the respective sanitiser. In order to keep +memory utilisation at a manageable level, you can either enforce limits at +the OS level (e.g. cgroups on Linux), or patch libcbor with the diff below. +N.B., the patch below is relative to libcbor 0.10.1. + +diff --git src/cbor/internal/memory_utils.c src/cbor/internal/memory_utils.c +index bbea63c..3f7c9af 100644 +--- src/cbor/internal/memory_utils.c ++++ src/cbor/internal/memory_utils.c +@@ -41,7 +41,11 @@ size_t _cbor_safe_signaling_add(size_t a, size_t b) { + + void* _cbor_alloc_multiple(size_t item_size, size_t item_count) { + if (_cbor_safe_to_multiply(item_size, item_count)) { +- return _cbor_malloc(item_size * item_count); ++ if (item_count > 1000) { ++ return NULL; ++ } else { ++ return _cbor_malloc(item_size * item_count); ++ } + } else { + return NULL; + } |