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: bugs@openldap.org Reporter: kangyang126@gmail.com 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; } ```