https://bugs.openldap.org/show_bug.cgi?id=10449
Issue ID: 10449
Summary: memory leak in parseReadAttrs
Product: OpenLDAP
Version: 2.6.12
Hardware: x86_64
OS: Linux
Status: UNCONFIRMED
Keywords: needs_review
Severity: normal
Priority: ---
Component: slapd
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
# ASAN Leak Report: Pre-read / Post-read Control Attributes
## Component
* **File:** `servers/slapd/controls.c`
* **Function:** `parseReadAttrs`
## Issue Description
**LeakSanitizer Error:** Memory leak detected in `AttributeName` array.
```plaintext
==202371==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 80 byte(s) in 1 object(s) allocated from:
#0 0x555555963614 in malloc
/src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:67:3
#1 0x555555f578d4 in ber_memalloc_x
/src/openldap/libraries/liblber/memory.c:228:9
#2 0x555555f4c5e2 in ber_get_stringbvl
/src/openldap/libraries/liblber/decode.c:421:14
#3 0x555555f4ac2f in ber_scanf
/src/openldap/libraries/liblber/decode.c:815:9
#4 0x555555b150e4 in parseReadAttrs
/src/openldap/servers/slapd/controls.c:1514:7
#5 0x555555b0d13c in slap_parse_ctrl
/src/openldap/servers/slapd/controls.c:738:10
#6 0x555555b0e101 in get_ctrls2
/src/openldap/servers/slapd/controls.c:929:16
#7 0x555555a35c0e in do_modrdn /src/openldap/servers/slapd/modrdn.c:129:6
#8 0x5555559e055d in connection_operation
/src/openldap/servers/slapd/connection.c:1137:7
#9 0x5555559df327 in connection_read_thread
/src/openldap/servers/slapd/connection.c:1289:14
#10 0x5555559a769a in LLVMFuzzerTestOneInput /src/fuzz_slapd.c:88:5
```
The function `parseReadAttrs` uses `ber_scanf` with the `M` format specifier to
allocate an array of `AttributeName` structures.
1. **Memory Leak:** This array was not freed if the function encountered an
error (e.g., critical control verification failure) after the allocation.
2. **Invalid Free:** Attempting to free `bv_val` strings inside the array
caused an "attempting free on address which was not malloc()-ed" error, because
these pointers refer to the internal `BerElement` buffer.
3. **Segmentation Fault:** Accessing the array to write a terminator without
checking for `NULL` caused a crash on empty attribute lists.
## Fix
* **Leak Fix:** Added comprehensive cleanup logic at the `done` label to free
the `AttributeName` array if an error occurs.
* **Logic Fix:** Refactored the loop to filter attributes without attempting
to free the internal string pointers, avoiding the `Invalid Free` error.
## Diff
```diff
diff --git a/servers/slapd/controls.c b/servers/slapd/controls.c
index 3d18345..3c90884 100644
--- a/servers/slapd/controls.c
+++ b/servers/slapd/controls.c
@@ -1476,7 +1476,7 @@ parseReadAttrs(
LDAPControl *ctrl,
int post )
{
- ber_len_t siz, off, i;
+ ber_len_t siz, off, i, good_i = 0;
BerElement *ber;
AttributeName *an = NULL;
@@ -1520,14 +1520,16 @@ parseReadAttrs(
for ( i = 0; i < siz; i++ ) {
const char *dummy = NULL;
int rc;
+ struct berval name = an[i].an_name;
an[i].an_desc = NULL;
an[i].an_oc = NULL;
an[i].an_flags = 0;
- rc = slap_bv2ad( &an[i].an_name, &an[i].an_desc, &dummy );
+ rc = slap_bv2ad( &name, &an[i].an_desc, &dummy );
if ( rc == LDAP_SUCCESS ) {
- an[i].an_name = an[i].an_desc->ad_cname;
-
+ an[good_i] = an[i];
+ an[good_i].an_name = an[good_i].an_desc->ad_cname;
+ good_i++;
} else {
int j;
static struct berval special_attrs[] = {
@@ -1537,23 +1539,29 @@ parseReadAttrs(
BER_BVNULL
};
- /* deal with special attribute types */
for ( j = 0; !BER_BVISNULL( &special_attrs[ j ] ); j++
) {
- if ( bvmatch( &an[i].an_name, &special_attrs[ j
] ) ) {
- an[i].an_name = special_attrs[ j ];
+ if ( bvmatch( &name, &special_attrs[ j ] ) ) {
+ an[good_i] = an[i];
+ an[good_i].an_name = special_attrs[ j
];
+ good_i++;
break;
}
}
- if ( BER_BVISNULL( &special_attrs[ j ] ) &&
ctrl->ldctl_iscritical ) {
- rs->sr_err = rc;
- rs->sr_text = dummy ? dummy
- : READMSG( post, "unknown
attributeType" );
- goto done;
+ if ( BER_BVISNULL( &special_attrs[ j ] ) ) {
+ if ( ctrl->ldctl_iscritical ) {
+ rs->sr_err = rc;
+ rs->sr_text = dummy ? dummy
+ : READMSG( post, "unknown
attributeType" );
+ goto done;
+ }
}
}
}
+ if ( an )
+ BER_BVZERO( &an[good_i].an_name );
+
if ( post ) {
op->o_postread_attrs = an;
op->o_postread = ctrl->ldctl_iscritical
@@ -1568,6 +1576,9 @@ parseReadAttrs(
done:
(void) ber_free( ber, 1 );
+ if ( rs->sr_err != LDAP_SUCCESS && an ) {
+ ber_memfree( an );
+ }
return rs->sr_err;
}
```
## 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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