From: Andrzej Hunt <ajrhunt@xxxxxxxxxx>
The primary goal of this change is to stop leaking init_db_template_dir.
This leak can happen because:
1. git_init_db_config() allocates new memory into init_db_template_dir
without first freeing the existing value.
2. init_db_template_dir might already contain data, either because:
2.1 git_config() can be invoked twice with this callback in a single
process - at least 2 allocations are likely.
2.2 A single git_config() allocation can invoke the callback multiple
times for a given key (see further explanation in the function
docs) - each of those calls will trigger another leak.
The simplest fix for the leak would be to free(init_db_template_dir)
before overwriting it. Instead we choose to convert to fetching
init.templatedir via git_config_get_value() as that is more explicit,
more efficient, and avoids allocations (the returned result is owned by
the config cache, so we aren't responsible for freeing it).
If we remove init_db_template_dir, git_init_db_config() ends up being
responsible only for forwarding core.* config values to
platform_core_config(). However platform_core_config() already ignores
non-core.* config values, so we can safely remove git_init_db_config()
and invoke git_config() directly with platform_core_config() as the
callback.
The platform_core_config forwarding was originally added in:
287853392a (mingw: respect core.hidedotfiles = false in git-init again, 2019-03-11
And I suspect the potential for a leak existed since the original
implementation of git_init_db_config in:
90b45187ba (Add `init.templatedir` configuration variable., 2010-02-17)
LSAN output from t0001:
Direct leak of 73 byte(s) in 1 object(s) allocated from:
#0 0x49a859 in realloc /home/abuild/rpmbuild/BUILD/llvm-11.0.0.src/build/../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:164:3
#1 0x9a7276 in xrealloc /home/ahunt/oss-fuzz/git/wrapper.c:126:8
#2 0x9362ad in strbuf_grow /home/ahunt/oss-fuzz/git/strbuf.c:98:2
#3 0x936eaa in strbuf_add /home/ahunt/oss-fuzz/git/strbuf.c:295:2
#4 0x868112 in strbuf_addstr /home/ahunt/oss-fuzz/git/./strbuf.h:304:2
#5 0x86a8ad in expand_user_path /home/ahunt/oss-fuzz/git/path.c:758:2
#6 0x720bb1 in git_config_pathname /home/ahunt/oss-fuzz/git/config.c:1287:10
#7 0x5960e2 in git_init_db_config /home/ahunt/oss-fuzz/git/builtin/init-db.c:161:11
#8 0x7255b8 in configset_iter /home/ahunt/oss-fuzz/git/config.c:1982:7
#9 0x7253fc in repo_config /home/ahunt/oss-fuzz/git/config.c:2311:2
#10 0x725ca7 in git_config /home/ahunt/oss-fuzz/git/config.c:2399:2
#11 0x593e8d in create_default_files /home/ahunt/oss-fuzz/git/builtin/init-db.c:225:2
#12 0x5935c6 in init_db /home/ahunt/oss-fuzz/git/builtin/init-db.c:449:11
#13 0x59588e in cmd_init_db /home/ahunt/oss-fuzz/git/builtin/init-db.c:714:9
#14 0x4cd60d in run_builtin /home/ahunt/oss-fuzz/git/git.c:453:11
#15 0x4cb2da in handle_builtin /home/ahunt/oss-fuzz/git/git.c:704:3
#16 0x4ccc37 in run_argv /home/ahunt/oss-fuzz/git/git.c:771:4
#17 0x4cac29 in cmd_main /home/ahunt/oss-fuzz/git/git.c:902:19
#18 0x69c4de in main /home/ahunt/oss-fuzz/git/common-main.c:52:11
#19 0x7f23552d6349 in __libc_start_main (/lib64/libc.so.6+0x24349)
Signed-off-by: Andrzej Hunt <ajrhunt@xxxxxxxxxx>
---
builtin/init-db.c | 28 +++++++---------------------
1 file changed, 7 insertions(+), 21 deletions(-)
diff --git a/builtin/init-db.c b/builtin/init-db.c
index dcc45bef5148..d31dbc883746 100644
--- a/builtin/init-db.c
+++ b/builtin/init-db.c
@@ -25,7 +25,6 @@
static int init_is_bare_repository = 0;
static int init_shared_repository = -1;
-static const char *init_db_template_dir;
static void copy_templates_1(struct strbuf *path, struct strbuf *template_path,
DIR *dir)
@@ -94,7 +93,7 @@ static void copy_templates_1(struct strbuf *path, struct strbuf *template_path,
}
}
-static void copy_templates(const char *template_dir)
+static void copy_templates(const char *template_dir, const char *init_template_dir)
{
struct strbuf path = STRBUF_INIT;
struct strbuf template_path = STRBUF_INIT;
@@ -107,7 +106,7 @@ static void copy_templates(const char *template_dir)
if (!template_dir)
template_dir = getenv(TEMPLATE_DIR_ENVIRONMENT);
if (!template_dir)
- template_dir = init_db_template_dir;
+ template_dir = init_template_dir;
if (!template_dir)
template_dir = to_free = system_path(DEFAULT_GIT_TEMPLATE_DIR);
if (!template_dir[0]) {
@@ -154,17 +153,6 @@ static void copy_templates(const char *template_dir)
clear_repository_format(&template_format);
}
-static int git_init_db_config(const char *k, const char *v, void *cb)
-{
- if (!strcmp(k, "init.templatedir"))
- return git_config_pathname(&init_db_template_dir, k, v);
-
- if (starts_with(k, "core."))
- return platform_core_config(k, v, cb);
-
- return 0;
-}
-
/*
* If the git_dir is not directly inside the working tree, then git will not
* find it by default, and we need to set the worktree explicitly.
@@ -212,10 +200,7 @@ static int create_default_files(const char *template_path,
int reinit;
int filemode;
struct strbuf err = STRBUF_INIT;
-
- /* Just look for `init.templatedir` */
- init_db_template_dir = NULL; /* re-set in case it was set before */
- git_config(git_init_db_config, NULL);
+ const char *init_template_dir = NULL;
/*
* First copy the templates -- we might have the default
@@ -226,7 +211,8 @@ static int create_default_files(const char *template_path,
* values (since we've just potentially changed what's available on
* disk).
*/
- copy_templates(template_path);
+ git_config_get_value("init.templatedir", &init_template_dir);
+ copy_templates(template_path, init_template_dir);
git_config_clear();
reset_shared_repository();
git_config(git_default_config, NULL);
@@ -422,8 +408,8 @@ int init_db(const char *git_dir, const char *real_git_dir,
}
startup_info->have_repository = 1;
- /* Just look for `core.hidedotfiles` */
- git_config(git_init_db_config, NULL);
+ /* Ensure `core.hidedotfiles` is processed */
+ git_config(platform_core_config, NULL);
safe_create_dir(git_dir, 0);
--
gitgitgadget
