fuzz: add fuzz_lzxpress_huffman_compress

This differs from fuzz_lzxpress_huffman_round_trip (next commit) in
that the output buffer might be too small for the compressed data, in
which case we want to see an error and not a crash.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Joseph Sutton <josephsutton@catalyst.net.nz>

2 files changed, 63 insertions, 0 deletions

diff --git a/lib/fuzzing/fuzz_lzxpress_huffman_compress.c b/lib/fuzzing/fuzz_lzxpress_huffman_compress.c
new file mode 100644
index 00000000000..d92131d3a8b
--- /dev/null
+++ b/lib/fuzzing/fuzz_lzxpress_huffman_compress.c
@@ -0,0 +1,58 @@
+/*
+   Fuzzing for lzxpress_huffman_compress_talloc
+   Copyright (C) Michael Hanselmann 2019
+   Copyright (C) Douglas Bagnall 2022 <dbagnall@samba.org>
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include "fuzzing/fuzzing.h"
+#include "compression/lzxpress_huffman.h"
+
+int LLVMFuzzerInitialize(int *argc, char ***argv)
+{
+	return 0;
+}
+
+
+#define MAX_SIZE (1024 * 1024)
+
+int LLVMFuzzerTestOneInput(uint8_t *buf, size_t len)
+{
+	static uint8_t *output;
+	size_t output_len;
+	TALLOC_CTX *mem_ctx = NULL;
+	struct lzxhuff_compressor_mem cmp_mem;
+
+	/*
+	 * The round-trip fuzzer checks the compressor with an unconstrained
+	 * output buffer; here we see what happens if the buffer is possibly too
+	 * small.
+	 */
+	if (len < 3) {
+		return 0;
+	}
+	output_len = MIN(MAX_SIZE, buf[0] | (buf[1] << 8) | (buf[2] << 16));
+	buf += 3;
+	len -= 3;
+	mem_ctx = talloc_new(NULL);
+
+	output = talloc_array(mem_ctx, uint8_t, output_len);
+
+	lzxpress_huffman_compress(&cmp_mem, buf, len, output, output_len);
+
+	talloc_free(mem_ctx);
+	return 0;
+}
diff --git a/lib/fuzzing/wscript_build b/lib/fuzzing/wscript_build
index 600c827e31e..fe64cec6c4e 100644
--- a/lib/fuzzing/wscript_build
+++ b/lib/fuzzing/wscript_build
@@ -62,6 +62,11 @@ bld.SAMBA_BINARY('fuzz_lzxpress_huffman_decompress',
                  deps='fuzzing LZXPRESS afl-fuzz-main',
                  fuzzer=True)
 
+bld.SAMBA_BINARY('fuzz_lzxpress_huffman_compress',
+                 source='fuzz_lzxpress_huffman_compress.c',
+                 deps='fuzzing LZXPRESS afl-fuzz-main',
+                 fuzzer=True)
+
 bld.SAMBA_BINARY('fuzz_ldap_decode',
                  source='fuzz_ldap_decode.c',
                  deps='fuzzing cli-ldap afl-fuzz-main',