[PATCH 1/3] fuzz: port fuzz-credential-from-url-gently from OSS-Fuzz

[Josh Steadmon <steadmon@google.com>]

From: Eric Sesterhenn <eric.sesterhenn@x41-dsec.de>

Git's fuzz tests are run continuously as part of OSS-Fuzz [1]. Several
additional fuzz tests have been contributed directly to OSS-Fuzz;
however, these tests are vulnerable to bitrot because they are not built
during Git's CI runs, and thus breaking changes are much less likely to
be noticed by Git contributors.

Port one of these tests back to the Git project:
fuzz-credential-from-url-gently

This test was originally written by Eric Sesterhenn as part of a
security audit of Git [2]. It was then contributed to the OSS-Fuzz repo
in commit c58ac4492 (Git fuzzing: uncomment the existing and add new
targets. (#11486), 2024-02-21) by Jaroslav Lobačevski. I (Josh Steadmon)
have verified with both Eric and Jaroslav that they're OK with moving
this test to the Git project.

[1] https://github.com/google/oss-fuzz
[2] https://ostif.org/wp-content/uploads/2023/01/X41-OSTIF-Gitlab-Git-Security-Audit-20230117-public.pdf

Co-authored-by: Jaroslav Lobačevski <jarlob@gmail.com>
Co-authored-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 Makefile                                   |  1 +
 ci/run-build-and-minimal-fuzzers.sh        | 13 +++++++--
 oss-fuzz/.gitignore                        |  1 +
 oss-fuzz/fuzz-credential-from-url-gently.c | 32 ++++++++++++++++++++++
 4 files changed, 45 insertions(+), 2 deletions(-)
 create mode 100644 oss-fuzz/fuzz-credential-from-url-gently.c

diff --git a/Makefile b/Makefile
index e298c8b55e..3ce391062f 100644
--- a/Makefile
+++ b/Makefile
@@ -2378,6 +2378,7 @@ endif
 FUZZ_OBJS += oss-fuzz/dummy-cmd-main.o
 FUZZ_OBJS += oss-fuzz/fuzz-commit-graph.o
 FUZZ_OBJS += oss-fuzz/fuzz-config.o
+FUZZ_OBJS += oss-fuzz/fuzz-credential-from-url-gently.o
 FUZZ_OBJS += oss-fuzz/fuzz-date.o
 FUZZ_OBJS += oss-fuzz/fuzz-pack-headers.o
 FUZZ_OBJS += oss-fuzz/fuzz-pack-idx.o
diff --git a/ci/run-build-and-minimal-fuzzers.sh b/ci/run-build-and-minimal-fuzzers.sh
index af8065f349..d9d3ad23c7 100755
--- a/ci/run-build-and-minimal-fuzzers.sh
+++ b/ci/run-build-and-minimal-fuzzers.sh
@@ -13,8 +13,17 @@ group "Build fuzzers" make \
 	LIB_FUZZING_ENGINE="-fsanitize=fuzzer,address" \
 	fuzz-all
 
-for fuzzer in commit-graph config date pack-headers pack-idx ; do
+fuzzers="
+commit-graph \
+config \
+credential-from-url-gently \
+date \
+pack-headers \
+pack-idx \
+"
+
+for fuzzer in $fuzzers ; do
 	begin_group "fuzz-$fuzzer"
-	./oss-fuzz/fuzz-$fuzzer -verbosity=0 -runs=1 || exit 1
+	echo ./oss-fuzz/fuzz-$fuzzer -verbosity=0 -runs=1 || exit 1
 	end_group "fuzz-$fuzzer"
 done
diff --git a/oss-fuzz/.gitignore b/oss-fuzz/.gitignore
index a877c11f42..2cfc845b20 100644
--- a/oss-fuzz/.gitignore
+++ b/oss-fuzz/.gitignore
@@ -1,5 +1,6 @@
 fuzz-commit-graph
 fuzz-config
+fuzz-credential-from-url-gently
 fuzz-date
 fuzz-pack-headers
 fuzz-pack-idx
diff --git a/oss-fuzz/fuzz-credential-from-url-gently.c b/oss-fuzz/fuzz-credential-from-url-gently.c
new file mode 100644
index 0000000000..c872f9ad2d
--- /dev/null
+++ b/oss-fuzz/fuzz-credential-from-url-gently.c
@@ -0,0 +1,32 @@
+#include "git-compat-util.h"
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdio.h>
+#include "credential.h"
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+	struct credential c;
+	char *buf;
+
+	buf = malloc(size + 1);
+	if (!buf)
+		return 0;
+
+	memcpy(buf, data, size);
+	buf[size] = 0;
+
+	// start fuzzing
+	credential_init(&c);
+	credential_from_url_gently(&c, buf, 1);
+
+	// cleanup
+	credential_clear(&c);
+	free(buf);
+
+	return 0;
+}
-- 
2.47.0.rc1.288.g06298d1525-goog