Add README that describes the libfuzzer integration. (#14856)

.github/.wordlist.txt

@@ -64,6 +64,7 @@ argv
 armeabi
 ARMmbed
 armv
+ASAN
 asdk
 AssertionError
 ASYNC
@@ -143,6 +144,7 @@ capacitive
 CatalogVendorId
 CBB
 cbd
+ccf
 CCMP
 CCS
 CCSTUDIO
@@ -302,6 +304,7 @@ DevKitC
 DevKitM
 df
 dfu
+DgDxsfHx
 dhclient
 DHCP
 DHCPC
@@ -413,6 +416,7 @@ ffeebaefa
 FFF
 fffe
 fffff
+fHtcwcAAAAAAAAAwQAAAAAAXPMlAAAAAAA
 Fi
 filepath
 fini
@@ -429,6 +433,7 @@ fstab
 fsync
 ftd
 fullclean
+fuzzer
 gbl
 gcloud
 GDB
@@ -571,6 +576,7 @@ libdbus
 LIBDIR
 libegl
 libffi
+libfuzzer
 libgirepository
 libglib
 libical
@@ -1134,7 +1140,9 @@ WSTK
 xa
 xab
 xaver
+xb
 xbef
+xc
 xcd
 Xcode
 xcodeproj
@@ -1143,6 +1151,7 @@ xd
 xdeadbeefcafe
 xds
 xdsdfu
+xed
 xef
 xF
 xFFFF

examples/all-clusters-app/linux/README.md

@@ -0,0 +1,58 @@
+# Matter Linux/Mac All Clusters Example
+
+## Fuzzing integration
+
+This example supports compilation with libfuzzer enabled.
+
+### Compiling with fuzzing enabled
+
+To compile with libfuzzer enabled on Mac, run:
+
+    $ ./scripts/run_in_build_env.sh "./scripts/build/build_examples.py --target darwin-x64-all-clusters-no-ble-asan-libfuzzer build"
+
+at the top level of the Matter tree.
+
+Similarly, to compile on Linux run:
+
+    $ ./scripts/run_in_build_env.sh "./scripts/build/build_examples.py --target linux-x64-all-clusters-no-ble-asan-libfuzzer build"
+
+### Running libfuzzer-enabled binaries
+
+#### Initial run
+
+To run the resulting binary with no particular inputs do:
+
+    $ ./out/darwin-x64-all-clusters-no-ble-asan-libfuzzer/chip-all-clusters-app-fuzzing
+
+or
+
+    $ ./out/linux-x64-all-clusters-no-ble-asan-libfuzzer/chip-all-clusters-app-fuzzing
+
+If this crashes, it will output the input that caused the crash in a variety of
+formats, looking something like this:
+
+    0xe,0x0,0xf1,0xb1,0xf1,0xf1,0xf1,0xf1,0xed,0x73,0x7,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0xc1,0x0,0x0,0x0,0x0,0x0,0x5c,0xf3,0x25,0x0,0x0,0x0,0x0,0x0,
+    \016\000\361\261\361\361\361\361\355s\007\000\000\000\000\000\000\000\301\000\000\000\000\000\\\363%\000\000\000\000\000
+    artifact_prefix='./'; Test unit written to ./crash-c9fd2434ccf4a33a7f49765dcc519e1fd529a8e5
+    Base64: DgDxsfHx8fHtcwcAAAAAAAAAwQAAAAAAXPMlAAAAAAA=
+
+Note that this creates a file holding the input that caused the crash.
+
+#### Run with a fixed input
+
+To run the binary with a specific input, place the input bytes in a file (which
+a crashing run of the fuzzer does automatically). If `$(INPUT_FILE)` is the name
+of that file, then run:
+
+    $ ./out/darwin-x64-all-clusters-no-ble-asan-libfuzzer/chip-all-clusters-app-fuzzing $(INPUT_FILE)
+
+or
+
+    $ ./out/linux-x64-all-clusters-no-ble-asan-libfuzzer/chip-all-clusters-app-fuzzing $(INPUT_FILE)
+
+#### Additional execution options.
+
+The binary can be run with `-help=1` to see more available options.
+
+Running with `ASAN_OPTIONS="handle_abort=2"` set in the environment may produce
+nicer stack traces.