Re: [PATCH v2] reflog: close leak of reflog expire entry

From: Jacob Keller <redacted>

find_cfg_ent() allocates a struct reflog_expire_entry_option via
FLEX_ALLOC_MEM and inserts it into a linked list in the
reflog_expire_options structure. The entries in this list are never
freed, resulting in a leak in cmd_reflog_expire and the gc reflog expire
maintenance task:

Direct leak of 39 byte(s) in 1 object(s) allocated from:
   #0 0x7ff975ee6883 in calloc (/lib64/libasan.so.8+0xe6883)
   #1 0x0000010edada in xcalloc ../wrapper.c:154
   #2 0x000000df0898 in find_cfg_ent ../reflog.c:28
   #3 0x000000df0898 in reflog_expire_config ../reflog.c:70
   #4 0x00000095c451 in configset_iter ../config.c:2116
   #5 0x0000006d29e7 in git_config ../config.h:724
   #6 0x0000006d29e7 in cmd_reflog_expire ../builtin/reflog.c:205
   #7 0x0000006d504c in cmd_reflog ../builtin/reflog.c:419
   #8 0x0000007e4054 in run_builtin ../git.c:480
   #9 0x0000007e4054 in handle_builtin ../git.c:746
   #10 0x0000007e8a35 in run_argv ../git.c:813
   #11 0x0000007e8a35 in cmd_main ../git.c:953
   #12 0x000000441e8f in main ../common-main.c:9
   #13 0x7ff9754115f4 in __libc_start_call_main (/lib64/libc.so.6+0x35f4)
   #14 0x7ff9754116a7 in __libc_start_main@@GLIBC_2.34 (/lib64/libc.so.6+0x36a7)
   #15 0x000000444184 in _start (/home/jekeller/libexec/git-core/git+0x444184)

Close this leak by adding a reflog_clear_expire_config() function which
iterates the linked list and frees its elements. Call it upon exit of
cmd_reflog_expire() and in reflog_expiry_cleanup().

Signed-off-by: Jacob Keller <redacted>
---
Changes in v2:
- Actually fix the leak properly. (Thanks Jeff for catching my brain fart!)
- Link to v1: https://lore.kernel.org/r/20250709-jk-fix-leak-reflog-expire-config-v1-1-34d5461cf8f5@gmail.com (local)
---
reflog.h         |  2 ++
builtin/reflog.c |  3 +++
reflog.c         | 15 +++++++++++++++
3 files changed, 20 insertions(+)

diff --git a/reflog.h b/reflog.h
index 63bb56280f4e..74b3f3c4f0ac 100644
--- a/reflog.h
+++ b/reflog.h

@@ -34,6 +34,8 @@ struct reflog_expire_options {

int reflog_expire_config(const char *var, const char *value,
const struct config_context *ctx, void *cb);

+void reflog_clear_expire_config(struct reflog_expire_options *opts);
+
/*
 * Adapt the options so that they apply to the given refname. This applies any
 * per-reference reflog expiry configuration that may exist to the options.

diff --git a/builtin/reflog.c b/builtin/reflog.c
index 3acaf3e32c27..d4da41aaea73 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c

@@ -283,6 +283,9 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix,
    &cb);

free(ref);
}
+
+ reflog_clear_expire_config(&opts);
+
return status;
}

diff --git a/reflog.c b/reflog.c
index 15d81ebea978..3ce1780924dd 100644
--- a/reflog.c
+++ b/reflog.c

@@ -81,6 +81,20 @@ int reflog_expire_config(const char *var, const char *value,

return 0;
}

+void reflog_clear_expire_config(struct reflog_expire_options *opts)
+{
+ struct reflog_expire_entry_option *ent = opts->entries, *tmp;
+
+ while (ent) {
+ tmp = ent;
+ ent = ent->next;
+ free(tmp);
+ }
+
+ opts->entries = NULL;
+ opts->entries_tail = NULL;
+}
+

void reflog_expire_options_set_refname(struct reflog_expire_options *cb,
      const char *ref)
{

@@ -490,6 +504,7 @@ void reflog_expiry_cleanup(void *cb_data)

for (elem = cb->mark_list; elem; elem = elem->next)
clear_commit_marks(elem->item, REACHABLE);
free_commit_list(cb->mark_list);
+ reflog_clear_expire_config(&cb->opts);
}

int count_reflog_ent(struct object_id *ooid UNUSED,