https://bugs.openldap.org/show_bug.cgi?id=10448
Issue ID: 10448
Summary: Memory leak in syncprov_parseCtrl
Product: OpenLDAP
Version: 2.6.12
Hardware: x86_64
OS: Linux
Status: UNCONFIRMED
Keywords: needs_review
Severity: normal
Priority: ---
Component: overlays
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
# ASAN Leak Report: Sync Provider Control
## Component
* **File:** `servers/slapd/overlays/syncprov.c`
* **Function:** `syncprov_parseCtrl`
## Issue Description
**LeakSanitizer Error:** Memory leak of `sync_control` structure.
```plaintext
==266290==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 80 byte(s) in 1 object(s) allocated from:
#0 0x555555964614 in malloc
/src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:67:3
#1 0x555555f58a04 in ber_memalloc_x
/src/openldap/libraries/liblber/memory.c:228:9
#2 0x555555a7cb06 in ch_malloc
/src/openldap/servers/slapd/ch_malloc.c:54:23
#3 0x555555b3ba6c in slap_sl_calloc
/src/openldap/servers/slapd/sl_malloc.c:401:12
#4 0x555555ca1734 in syncprov_parseCtrl
/src/openldap/servers/slapd/overlays/syncprov.c:4333:7
#5 0x555555b0e13c in slap_parse_ctrl
/src/openldap/servers/slapd/controls.c:738:10
#6 0x555555b0f101 in get_ctrls2
/src/openldap/servers/slapd/controls.c:929:16
#7 0x555555a30eae in do_search /src/openldap/servers/slapd/search.c:194:6
#8 0x5555559e155d in connection_operation
/src/openldap/servers/slapd/connection.c:1137:7
#9 0x5555559e0327 in connection_read_thread
/src/openldap/servers/slapd/connection.c:1289:14
#10 0x5555559a869a in LLVMFuzzerTestOneInput /src/fuzz_slapd.c:88:5
```
The `syncprov` overlay allocates a specific `sync_control` structure and
attaches it to the operation's control list (`op->o_controls`) when parsing the
`LDAP_CONTROL_SYNC`.
* **Leak:** The core server's cleanup routine (`slap_free_ctrls`) is unaware
of this overlay-specific structure. If the operation is abandoned or fails
(e.g., during parsing of subsequent controls), the `sync_control` and its
internal allocations (context CSNs, session IDs) are never freed.
## Fix
* **Cleanup Callback:** Defined a new callback function
`syncprov_ctrl_cleanup` that properly frees the `sync_control` structure.
* **Registration:** Updated `syncprov_parseCtrl` to register this callback
(`op->o_callback`) immediately after allocating the control. This ensures
`slap_cleanup_play` invokes the cleanup routine during operation teardown,
preventing the leak.
## Diff
```diff
diff --git a/servers/slapd/overlays/syncprov.c
b/servers/slapd/overlays/syncprov.c
index 042d742..7257f79 100644
--- a/servers/slapd/overlays/syncprov.c
+++ b/servers/slapd/overlays/syncprov.c
@@ -4246,6 +4246,26 @@ syncprov_db_destroy(
return 0;
}
+static int
+syncprov_ctrl_cleanup( Operation *op, SlapReply *rs )
+{
+ if ( op->o_controls[slap_cids.sc_LDAPsync] ) {
+ sync_control *sr = op->o_controls[slap_cids.sc_LDAPsync];
+ op->o_controls[slap_cids.sc_LDAPsync] = NULL;
+ if ( sr->sr_state.ctxcsn ) {
+ ber_bvarray_free_x( sr->sr_state.ctxcsn,
op->o_tmpmemctx );
+ }
+ if ( sr->sr_state.sids ) {
+ op->o_tmpfree( sr->sr_state.sids, op->o_tmpmemctx );
+ }
+ if ( sr->sr_state.octet_str.bv_val ) {
+ op->o_tmpfree( sr->sr_state.octet_str.bv_val,
op->o_tmpmemctx );
+ }
+ op->o_tmpfree( sr, op->o_tmpmemctx );
+ }
+ return slap_freeself_cb( op, rs );
+}
+
static int syncprov_parseCtrl (
Operation *op,
SlapReply *rs,
@@ -4353,6 +4373,13 @@ static int syncprov_parseCtrl (
op->o_sync_mode |= mode; /* o_sync_mode shares o_sync */
+ {
+ slap_callback *cb = op->o_tmpcalloc( 1, sizeof(slap_callback),
op->o_tmpmemctx );
+ cb->sc_cleanup = syncprov_ctrl_cleanup;
+ cb->sc_next = op->o_callback;
+ op->o_callback = cb;
+ }
+
return LDAP_SUCCESS;
}
```
## Harness
```
#define _GNU_SOURCE /* For memfd_create */
#include "portable.h"
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <signal.h>
#include "slap.h"
/* 1. Fix function declarations to match return types in OpenLDAP source code
*/
extern void slap_sl_mem_init( void );
extern int slapd_daemon_init( const char *urls );
extern int extops_init( void ); /* Returns int */
extern void lutil_passwd_init( void );
extern int slap_init( int mode, const char *name );
extern int read_config( const char *fname, const char *dname );
extern int connections_init( void ); /* Returns int */
extern int slap_startup( Backend *be );
void slapd_daemon_nothread( void ) {}
extern int ldap_pvt_thread_initialize( void ); /* Returns int */
extern void* ldap_pvt_thread_pool_context( void );
extern void* connection_read_thread( void *ctx, void *arg );
extern void connection_closing( Connection *c, const char *why );
extern int connection_resched( Connection *c );
extern Connection* connection_init( int sfd, Listener *l, const char *authid,
const char *dns, int flags, slap_ssf_t ssf, struct berval *authid_out );
extern ldap_pvt_thread_pool_t connection_pool;
static Listener *global_listener = NULL;
static struct berval authid_bv = {0, ""};
int LLVMFuzzerInitialize(int *argc, char ***argv) {
signal(SIGPIPE, SIG_IGN);
slap_debug = 0;
slap_sl_mem_init();
if ( 0 != slapd_daemon_init("ldapi://%2Ftmp%2Ffuzz.sock") ) return 1;
extops_init();
lutil_passwd_init();
if ( slap_init(SLAP_SERVER_MODE, "slapd-fuzz") ) return 2;
read_config( NULL, NULL );
connections_init();
slap_startup(NULL);
slapd_daemon_nothread();
ldap_pvt_thread_initialize();
global_listener = slapd_get_listeners()[0];
if (!global_listener) return 3;
return 0;
}
#include <sys/socket.h>
int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
if (Size < 2 || Size > 65536) return 0;
/* 2. Use socketpair to simulate socket read/write */
int sv[2];
if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv) < 0) return 0;
if (write(sv[0], Data, Size) != (ssize_t)Size) {
close(sv[0]);
close(sv[1]);
return 0;
}
/* Close write end so server receives EOF after reading data */
close(sv[0]);
/* 3. Create connection (server uses sv[1]) */
Connection *c = connection_init(sv[1], global_listener, "fuzz",
"IP=127.0.0.1", 0, 0, &authid_bv);
if (!c) {
close(sv[1]);
return 0;
}
void* ctx = ldap_pvt_thread_pool_context();
/* Execute parsing logic */
connection_read_thread(ctx, (void*)(long)sv[1]);
/* Wait for thread pool to complete all tasks to prevent background threads
from accessing freed connection */
int active = 0, pending = 0;
do {
ldap_pvt_thread_pool_query(&connection_pool,
LDAP_PVT_THREAD_POOL_PARAM_PENDING, &pending);
ldap_pvt_thread_pool_query(&connection_pool,
LDAP_PVT_THREAD_POOL_PARAM_ACTIVE, &active);
if (active == 0 && pending == 0) break;
ldap_pvt_thread_yield();
} while (1);
/* 4. Thoroughly clean up manually, avoiding unstable macros
* Directly manipulate queue pointers to ensure no 'error: use of
undeclared identifier o_next'
*/
Operation *op;
while ((op = LDAP_STAILQ_FIRST(&c->c_ops)) != NULL) {
LDAP_STAILQ_REMOVE_HEAD(&c->c_ops, o_next);
LDAP_STAILQ_NEXT(op, o_next) = NULL;
slap_op_free(op, ctx);
}
LDAP_STAILQ_INIT(&c->c_ops);
/* Close and reclaim Connection memory */
connection_closing(c, "fuzz complete");
connection_resched(c);
/* ldap_pvt_thread_pool_resume(&connection_pool); */
return 0;
}
```
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