[RFC PATCH 2/2] fuzz: Add fuzz testing for packfile indices.
Show changes to 5 files +56 −20
.gitignore, Makefile, fuzz-pack-idx.c, packfile.c, packfile.h
diff --git a/.gitignore b/.gitignore
index 87a28b3115..64b3377d40 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
/fuzz_corpora
/fuzz-pack-headers
+/fuzz-pack-idx
/GIT-BUILD-OPTIONS
/GIT-CFLAGS
/GIT-LDFLAGS
diff --git a/Makefile b/Makefile
index 10bb82b115..f7e6be8f19 100644
--- a/Makefile
+++ b/Makefile
@@ -685,6 +685,7 @@ SCRIPTS = $(SCRIPT_SH_INS) \
ETAGS_TARGET = TAGS
FUZZ_OBJS += fuzz-pack-headers.o
+FUZZ_OBJS += fuzz-pack-idx.o
FUZZ_PROGRAMS += $(patsubst %.o,%,$(FUZZ_OBJS))
@@ -3071,7 +3072,7 @@ cover_db_html: cover_db
### Fuzz testing
#
-.PHONY: fuzz-clean fuzz-objs fuzz-compile
+.PHONY: fuzz-clean fuzz-objs fuzz-compile fuzz-all
FUZZ_CFLAGS = $(CFLAGS) -fsanitize-coverage=trace-pc-guard -fsanitize=address
FUZZ_LDFLAGS = $(FUZZ_CFLAGS)
@@ -3089,3 +3090,5 @@ fuzz-compile:
$(FUZZ_PROGRAMS): fuzz-compile
clang++ $(FUZZ_LDFLAGS) $(LIB_OBJS) $(BUILTIN_OBJS) $(XDIFF_OBJS) \
$(EXTLIBS) git.o $@.o /usr/lib/llvm-4.0/lib/libFuzzer.a -o $@
+
+fuzz-all: $(FUZZ_PROGRAMS)
diff --git a/fuzz-pack-idx.c b/fuzz-pack-idx.c
new file mode 100644
index 0000000000..0c3d777aac
--- /dev/null
+++ b/fuzz-pack-idx.c
@@ -0,0 +1,13 @@
+#include "object-store.h"
+#include "packfile.h"
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+ struct packed_git p;
+
+ load_idx("fuzz-input", GIT_SHA1_RAWSZ, (void *)data, size, &p);
+
+ return 0;
+}
diff --git a/packfile.c b/packfile.c
index 841b36182f..86074a76e9 100644
--- a/packfile.c
+++ b/packfile.c
@@ -80,10 +80,8 @@ void pack_report(void)
static int check_packed_git_idx(const char *path, struct packed_git *p)
{
void *idx_map;
- struct pack_idx_header *hdr;
size_t idx_size;
- uint32_t version, nr, i, *index;
- int fd = git_open(path);
+ int fd = git_open(path), ret;
struct stat st;
const unsigned int hashsz = the_hash_algo->rawsz;
@@ -101,16 +99,32 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
- hdr = idx_map;
+ ret = load_idx(path, hashsz, idx_map, idx_size, p);
+
+ if (ret)
+ munmap(idx_map, idx_size);
+
+ return ret;
+}
+
+int load_idx(const char *path, const unsigned int hashsz, void *idx_map,
+ size_t idx_size, struct packed_git *p)
+{
+ struct pack_idx_header *hdr = idx_map;
+ uint32_t version, nr, i, *index;
+
+ if (idx_size < 4 * 256 + hashsz + hashsz)
+ return error("index file %s is too small", path);
+ if (idx_map == NULL)
+ return error("empty data");
+
if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
version = ntohl(hdr->idx_version);
- if (version < 2 || version > 2) {
- munmap(idx_map, idx_size);
+ if (version < 2 || version > 2)
return error("index file %s is version %"PRIu32
" and is not supported by this binary"
" (try upgrading GIT to a newer version)",
path, version);
- }
} else
version = 1;
@@ -120,10 +134,8 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
index += 2; /* skip index header */
for (i = 0; i < 256; i++) {
uint32_t n = ntohl(index[i]);
- if (n < nr) {
- munmap(idx_map, idx_size);
+ if (n < nr)
return error("non-monotonic index %s", path);
- }
nr = n;
}
@@ -135,10 +147,8 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
* - hash of the packfile
* - file checksum
*/
- if (idx_size != 4*256 + nr * (hashsz + 4) + hashsz + hashsz) {
- munmap(idx_map, idx_size);
+ if (idx_size != 4 * 256 + nr * (hashsz + 4) + hashsz + hashsz)
return error("wrong index v1 file size in %s", path);
- }
} else if (version == 2) {
/*
* Minimum size:
@@ -157,20 +167,16 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
unsigned long max_size = min_size;
if (nr)
max_size += (nr - 1)*8;
- if (idx_size < min_size || idx_size > max_size) {
- munmap(idx_map, idx_size);
+ if (idx_size < min_size || idx_size > max_size)
return error("wrong index v2 file size in %s", path);
- }
if (idx_size != min_size &&
/*
* make sure we can deal with large pack offsets.
* 31-bit signed offset won't be enough, neither
* 32-bit unsigned one will be.
*/
- (sizeof(off_t) <= 4)) {
- munmap(idx_map, idx_size);
+ (sizeof(off_t) <= 4))
return error("pack too large for current definition of off_t in %s", path);
- }
}
p->index_version = version;
diff --git a/packfile.h b/packfile.h
index 442625723d..6c4037605d 100644
--- a/packfile.h
+++ b/packfile.h
@@ -164,4 +164,17 @@ extern int has_pack_index(const unsigned char *sha1);
*/
extern int is_promisor_object(const struct object_id *oid);
+/*
+ * Expose a function for fuzz testing.
+ *
+ * load_idx() parses a block of memory as a packfile index and puts the results
+ * into a struct packed_git.
+ *
+ * This function should not be used directly. It is exposed here only so that we
+ * have a convenient entry-point for fuzz testing. For real uses, you should
+ * probably use open_pack_index() or parse_pack_index() instead.
+ */
+extern int load_idx(const char *path, const unsigned int hashsz, void *idx_map,
+ size_t idx_size, struct packed_git *p);
+
#endif
Josh Steadmon