From: Josh Steadmon <steadmon@google.com>
To: git@vger.kernel.org, stolee@gmail.com
Subject: [PATCH 1/2] commit-graph, fuzz: Add fuzzer for commit-graph
Date: Wed, 5 Dec 2018 14:32:50 -0800 [thread overview]
Message-ID: <53e62baaa8769bf8e90991e32e0d123cc6629559.1544048946.git.steadmon@google.com> (raw)
In-Reply-To: <cover.1544048946.git.steadmon@google.com>
Breaks load_commit_graph_one() into a new function,
parse_commit_graph(). The latter function operates on arbitrary buffers,
which makes it suitable as a fuzzing target.
Adds fuzz-commit-graph.c, which provides a fuzzing entry point
compatible with libFuzzer (and possibly other fuzzing engines).
Signed-off-by: Josh Steadmon <steadmon@google.com>
---
.gitignore | 1 +
Makefile | 1 +
commit-graph.c | 63 +++++++++++++++++++++++++++++++++------------
fuzz-commit-graph.c | 18 +++++++++++++
4 files changed, 66 insertions(+), 17 deletions(-)
create mode 100644 fuzz-commit-graph.c
diff --git a/.gitignore b/.gitignore
index 0d77ea5894..8bcf153ed9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+/fuzz-commit-graph
/fuzz_corpora
/fuzz-pack-headers
/fuzz-pack-idx
diff --git a/Makefile b/Makefile
index 1a44c811aa..6b72f37c29 100644
--- a/Makefile
+++ b/Makefile
@@ -684,6 +684,7 @@ SCRIPTS = $(SCRIPT_SH_INS) \
ETAGS_TARGET = TAGS
+FUZZ_OBJS += fuzz-commit-graph.o
FUZZ_OBJS += fuzz-pack-headers.o
FUZZ_OBJS += fuzz-pack-idx.o
diff --git a/commit-graph.c b/commit-graph.c
index 40c855f185..0755359b1a 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -46,6 +46,10 @@
#define GRAPH_MIN_SIZE (GRAPH_HEADER_SIZE + 4 * GRAPH_CHUNKLOOKUP_WIDTH \
+ GRAPH_FANOUT_SIZE + GRAPH_OID_LEN)
+struct commit_graph *parse_commit_graph(void *graph_map, int fd,
+ size_t graph_size);
+
+
char *get_commit_graph_filename(const char *obj_dir)
{
return xstrfmt("%s/info/commit-graph", obj_dir);
@@ -84,16 +88,10 @@ static int commit_graph_compatible(struct repository *r)
struct commit_graph *load_commit_graph_one(const char *graph_file)
{
void *graph_map;
- const unsigned char *data, *chunk_lookup;
size_t graph_size;
struct stat st;
- uint32_t i;
- struct commit_graph *graph;
+ struct commit_graph *ret;
int fd = git_open(graph_file);
- uint64_t last_chunk_offset;
- uint32_t last_chunk_id;
- uint32_t graph_signature;
- unsigned char graph_version, hash_version;
if (fd < 0)
return NULL;
@@ -108,27 +106,61 @@ struct commit_graph *load_commit_graph_one(const char *graph_file)
die(_("graph file %s is too small"), graph_file);
}
graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
+ ret = parse_commit_graph(graph_map, fd, graph_size);
+
+ if (ret == NULL) {
+ munmap(graph_map, graph_size);
+ close(fd);
+ exit(1);
+ }
+
+ return ret;
+}
+
+/*
+ * This function is intended to be used only from load_commit_graph_one() or in
+ * fuzz tests.
+ */
+struct commit_graph *parse_commit_graph(void *graph_map, int fd,
+ size_t graph_size)
+{
+ const unsigned char *data, *chunk_lookup;
+ uint32_t i;
+ struct commit_graph *graph;
+ uint64_t last_chunk_offset;
+ uint32_t last_chunk_id;
+ uint32_t graph_signature;
+ unsigned char graph_version, hash_version;
+
+ /*
+ * This should already be checked in load_commit_graph_one, but we still
+ * need a check here for when we're calling parse_commit_graph directly
+ * from fuzz tests. We can omit the error message in that case.
+ */
+ if (graph_size < GRAPH_MIN_SIZE)
+ return NULL;
+
data = (const unsigned char *)graph_map;
graph_signature = get_be32(data);
if (graph_signature != GRAPH_SIGNATURE) {
error(_("graph signature %X does not match signature %X"),
graph_signature, GRAPH_SIGNATURE);
- goto cleanup_fail;
+ return NULL;
}
graph_version = *(unsigned char*)(data + 4);
if (graph_version != GRAPH_VERSION) {
error(_("graph version %X does not match version %X"),
graph_version, GRAPH_VERSION);
- goto cleanup_fail;
+ return NULL;
}
hash_version = *(unsigned char*)(data + 5);
if (hash_version != GRAPH_OID_VERSION) {
error(_("hash version %X does not match version %X"),
hash_version, GRAPH_OID_VERSION);
- goto cleanup_fail;
+ return NULL;
}
graph = alloc_commit_graph();
@@ -152,7 +184,8 @@ struct commit_graph *load_commit_graph_one(const char *graph_file)
if (chunk_offset > graph_size - GIT_MAX_RAWSZ) {
error(_("improper chunk offset %08x%08x"), (uint32_t)(chunk_offset >> 32),
(uint32_t)chunk_offset);
- goto cleanup_fail;
+ free(graph);
+ return NULL;
}
switch (chunk_id) {
@@ -187,7 +220,8 @@ struct commit_graph *load_commit_graph_one(const char *graph_file)
if (chunk_repeated) {
error(_("chunk id %08x appears multiple times"), chunk_id);
- goto cleanup_fail;
+ free(graph);
+ return NULL;
}
if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
@@ -201,11 +235,6 @@ struct commit_graph *load_commit_graph_one(const char *graph_file)
}
return graph;
-
-cleanup_fail:
- munmap(graph_map, graph_size);
- close(fd);
- exit(1);
}
static void prepare_commit_graph_one(struct repository *r, const char *obj_dir)
diff --git a/fuzz-commit-graph.c b/fuzz-commit-graph.c
new file mode 100644
index 0000000000..420851d0d2
--- /dev/null
+++ b/fuzz-commit-graph.c
@@ -0,0 +1,18 @@
+#include "object-store.h"
+#include "commit-graph.h"
+
+struct commit_graph *parse_commit_graph(void *graph_map, int fd,
+ size_t graph_size);
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+ struct commit_graph *g;
+
+ g = parse_commit_graph((void *) data, -1, size);
+ if (g)
+ free(g);
+
+ return 0;
+}
--
2.20.0.rc2.403.gdbc3b29805-goog
next prev parent reply other threads:[~2018-12-05 22:32 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-05 22:32 [PATCH 0/2] Add commit-graph fuzzer and fix buffer overflow Josh Steadmon
2018-12-05 22:32 ` Josh Steadmon [this message]
2018-12-05 22:48 ` [PATCH 1/2] commit-graph, fuzz: Add fuzzer for commit-graph Ævar Arnfjörð Bjarmason
2018-12-06 1:00 ` Josh Steadmon
2018-12-06 1:32 ` Junio C Hamano
2018-12-06 1:41 ` Junio C Hamano
2018-12-06 4:47 ` Junio C Hamano
2018-12-05 22:32 ` [PATCH 2/2] commit-graph: fix buffer read-overflow Josh Steadmon
2018-12-06 13:11 ` Derrick Stolee
2018-12-06 20:20 ` [PATCH v2 0/3] Add commit-graph fuzzer and fix buffer overflow Josh Steadmon
2018-12-06 20:20 ` [PATCH v2 1/3] commit-graph, fuzz: Add fuzzer for commit-graph Josh Steadmon
2018-12-06 20:20 ` [PATCH v2 2/3] commit-graph: fix buffer read-overflow Josh Steadmon
2018-12-07 9:07 ` Jeff King
2018-12-07 13:33 ` Derrick Stolee
2018-12-06 20:20 ` [PATCH v2 3/3] Makefile: correct example fuzz build Josh Steadmon
2018-12-07 22:27 ` [PATCH v3 0/3] Add commit-graph fuzzer and fix buffer overflow Josh Steadmon
2018-12-07 22:27 ` [PATCH v3 1/3] commit-graph, fuzz: Add fuzzer for commit-graph Josh Steadmon
2018-12-07 22:27 ` [PATCH v3 2/3] commit-graph: fix buffer read-overflow Josh Steadmon
2018-12-09 4:01 ` Junio C Hamano
2018-12-10 4:28 ` SZEDER Gábor
2018-12-10 21:58 ` Josh Steadmon
2018-12-10 21:56 ` Josh Steadmon
2018-12-11 9:50 ` Jeff King
2018-12-07 22:27 ` [PATCH v3 3/3] Makefile: correct example fuzz build Josh Steadmon
2018-12-13 19:43 ` [PATCH v4 0/3] Add commit-graph fuzzer and fix buffer overflow Josh Steadmon
2018-12-13 19:43 ` [PATCH v4 1/3] commit-graph, fuzz: Add fuzzer for commit-graph Josh Steadmon
2018-12-13 19:43 ` [PATCH v4 2/3] commit-graph: fix buffer read-overflow Josh Steadmon
2019-01-12 10:57 ` SZEDER Gábor
2019-01-15 19:58 ` Josh Steadmon
2018-12-13 19:43 ` [PATCH v4 3/3] Makefile: correct example fuzz build Josh Steadmon
2018-12-18 17:35 ` [PATCH v4 0/3] Add commit-graph fuzzer and fix buffer overflow Jeff King
2018-12-18 21:05 ` Josh Steadmon
2018-12-19 15:51 ` Jeff King
2018-12-20 19:35 ` Johannes Schindelin
2018-12-20 20:11 ` Jeff King
2018-12-26 22:29 ` Junio C Hamano
2019-01-15 19:59 ` [PATCH v5 " Josh Steadmon
2019-01-15 19:59 ` [PATCH v5 1/3] commit-graph, fuzz: Add fuzzer for commit-graph Josh Steadmon
2019-01-15 20:33 ` Junio C Hamano
2019-01-15 19:59 ` [PATCH v5 2/3] commit-graph: fix buffer read-overflow Josh Steadmon
2019-01-15 19:59 ` [PATCH v5 3/3] Makefile: correct example fuzz build Josh Steadmon
2019-01-15 20:39 ` Junio C Hamano
2019-01-15 21:59 ` Josh Steadmon
2019-01-15 22:34 ` Junio C Hamano
2019-01-15 22:25 ` [PATCH v6 0/3] Add commit-graph fuzzer and fix buffer overflow Josh Steadmon
2019-01-15 22:25 ` [PATCH v6 1/3] commit-graph, fuzz: Add fuzzer for commit-graph Josh Steadmon
2019-01-15 22:25 ` [PATCH v6 2/3] commit-graph: fix buffer read-overflow Josh Steadmon
2019-02-20 14:55 ` Ævar Arnfjörð Bjarmason
2019-02-20 16:50 ` SZEDER Gábor
2019-01-15 22:25 ` [PATCH v6 3/3] Makefile: correct example fuzz build Josh Steadmon
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