38 lines
1.6 KiB
Plaintext
38 lines
1.6 KiB
Plaintext
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Fuzzing the lwIP stack (afl-fuzz requires linux/unix or similar)
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This directory contains a small app that reads Ethernet frames from stdin and
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processes them. It is used together with the 'american fuzzy lop' tool (found
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at http://lcamtuf.coredump.cx/afl/) and the sample inputs to test how
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unexpected inputs are handled. The afl tool will read the known inputs, and
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try to modify them to exercise as many code paths as possible, by instrumenting
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the code and keeping track of which code is executed.
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Just running make will produce the test program.
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Running make with parameter 'D=-DLWIP_FUZZ_MULTI_PACKET' will produce a binary
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that parses the input data as multiple packets (experimental!).
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Then run afl with:
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afl-fuzz -i inputs/<INPUT> -o output ./lwip_fuzz
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and it should start working. It will probably complain about CPU scheduler,
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set AFL_SKIP_CPUFREQ=1 to ignore it.
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If it complains about invalid "/proc/sys/kernel/core_pattern" setting, try
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executing "sudo bash -c 'echo core > /proc/sys/kernel/core_pattern'".
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The input is split into different subdirectories since they test different
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parts of the code, and since you want to run one instance of afl-fuzz on each
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core.
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When afl finds a crash or a hang, the input that caused it will be placed in
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the output directory. If you have hexdump and text2pcap tools installed,
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running output_to_pcap.sh <outputdir> will create pcap files for each input
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file to simplify viewing in wireshark.
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The lwipopts.h file needs to have checksum checking off, otherwise almost every
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packet will be discarded because of that. The other options can be tuned to
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expose different parts of the code.
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