From 751d063f27a1d3c77ef092d4737524c55c65d972 Mon Sep 17 00:00:00 2001
From: Eric Sesterhenn <eric.sesterhenn@x41-dsec.de>
Date: Mon, 14 Oct 2024 14:04:10 -0700
Subject: [PATCH] fuzz: port fuzz-url-decode-mem from OSS-Fuzz
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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-url-decode-mem

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>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 Makefile                            |  1 +
 ci/run-build-and-minimal-fuzzers.sh |  1 +
 oss-fuzz/.gitignore                 |  1 +
 oss-fuzz/fuzz-url-decode-mem.c      | 43 +++++++++++++++++++++++++++++
 4 files changed, 46 insertions(+)
 create mode 100644 oss-fuzz/fuzz-url-decode-mem.c

diff --git a/Makefile b/Makefile
index cfbbd70fdc..5d630eedaa 100644
--- a/Makefile
+++ b/Makefile
@@ -2427,6 +2427,7 @@ FUZZ_OBJS += oss-fuzz/fuzz-date.o
 FUZZ_OBJS += oss-fuzz/fuzz-pack-headers.o
 FUZZ_OBJS += oss-fuzz/fuzz-pack-idx.o
 FUZZ_OBJS += oss-fuzz/fuzz-parse-attr-line.o
+FUZZ_OBJS += oss-fuzz/fuzz-url-decode-mem.o
 .PHONY: fuzz-objs
 fuzz-objs: $(FUZZ_OBJS)
 
diff --git a/ci/run-build-and-minimal-fuzzers.sh b/ci/run-build-and-minimal-fuzzers.sh
index 13c85320d6..e7b97952e7 100755
--- a/ci/run-build-and-minimal-fuzzers.sh
+++ b/ci/run-build-and-minimal-fuzzers.sh
@@ -21,6 +21,7 @@ date
 pack-headers
 pack-idx
 parse-attr-line
+url-decode-mem
 "
 
 for fuzzer in $fuzzers; do
diff --git a/oss-fuzz/.gitignore b/oss-fuzz/.gitignore
index ec185f061c..f2d74de457 100644
--- a/oss-fuzz/.gitignore
+++ b/oss-fuzz/.gitignore
@@ -5,3 +5,4 @@ fuzz-date
 fuzz-pack-headers
 fuzz-pack-idx
 fuzz-parse-attr-line
+fuzz-url-decode-mem
diff --git a/oss-fuzz/fuzz-url-decode-mem.c b/oss-fuzz/fuzz-url-decode-mem.c
new file mode 100644
index 0000000000..2342aa993b
--- /dev/null
+++ b/oss-fuzz/fuzz-url-decode-mem.c
@@ -0,0 +1,43 @@
+#include "git-compat-util.h"
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdio.h>
+#include "url.h"
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+	char *buf;
+	char *r;
+	const char *pbuf;
+
+	buf = malloc(size + 1);
+	if (!buf)
+		return 0;
+
+	memcpy(buf, data, size);
+	buf[size] = 0;
+
+	// start fuzzing
+	r = url_decode(buf);
+	free(r);
+
+	r = url_percent_decode(buf);
+	free(r);
+
+	pbuf = (const char*) buf;
+	r = url_decode_parameter_name(&pbuf);
+	free(r);
+
+	pbuf = (const char*) buf;
+	r = url_decode_parameter_value(&pbuf);
+	free(r);
+
+	// cleanup
+	free(buf);
+
+	return 0;
+}