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. Since parse_commit_graph()
is only called by load_commit_graph_one() (and the fuzzer described
below), we omit error messages that would be duplicated by the caller.
Adds fuzz-commit-graph.c, which provides a fuzzing entry point
compatible with libFuzzer (and possibly other fuzzing engines).
Signed-off-by: Josh Steadmon <stead...@google.com>
---
.gitignore | 1 +
Makefile | 1 +
commit-graph.c | 53 ++++++++++++++++++++++++++++++---------------
commit-graph.h | 3 +++
fuzz-commit-graph.c | 16 ++++++++++++++
5 files changed, 57 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..07dd410f3c 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -84,16 +84,10 @@ 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 +102,55 @@ 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) {
+ munmap(graph_map, graph_size);
+ close(fd);
+ exit(1);
+ }
+
+ return ret;
+}
+
+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;
+
+ if (!graph_map)
+ return NULL;
+
+ 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 +174,8 @@ 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 +210,8 @@ 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 +225,6 @@ 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/commit-graph.h b/commit-graph.h
index 9db40b4d3a..813e7c19f1 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -54,6 +54,9 @@ struct commit_graph {
struct commit_graph *load_commit_graph_one(const char *graph_file);
+struct commit_graph *parse_commit_graph(void *graph_map, int fd,
+ size_t graph_size);
+
/*
* Return 1 if and only if the repository has a commit-graph
* file and generation numbers are computed in that file.
diff --git a/fuzz-commit-graph.c b/fuzz-commit-graph.c
new file mode 100644
index 0000000000..cf790c9d04
--- /dev/null
+++ b/fuzz-commit-graph.c
@@ -0,0 +1,16 @@
+#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);
+ free(g);
+
+ return 0;
+}
--
2.20.0.rc2.12.g4c11c11dec
