libmsc/sms_queue.c: fix memleak in smsq_take_next_sms()

A memleak has been noticed after executing some of TTCN-3 test
cases. For example, the following ones:

  - MSC_Tests.TC_lu_and_mo_sms,
  - MSC_Tests.TC_lu_and_mt_sms.

The key point is that MSC_Tests.TC_lu_and_mo_sms basically sends
a MO SMS to a non-attached subscriber with MSISDN 12345, so this
message is getting stored in the SMSC's database.

As soon as the SMSC's queue is triggered, sms_submit_pending() would
retrieve pending messages from the database by calling function
smsq_take_next_sms() in loop and attempt to deliver them.

This function in it's turn checks whether the subscriber is attached
or not. If not, the allocated 'gsm_sms' structure would not be
free()ed! Therefore, every time smsq_take_next_sms() is called,
one 'gsm_sms' structure for an unattached subscriber is leaked.

Furthermore, there is a unit test called 'sms_queue_test', that
actually does cover smsq_take_next_sms() and was designed to
catch some potential memory leaks, but...

In order to avoid emulating the low-level SQLite API, the unit
test by design overwrites some functions of libmsc, including
db_sms_get_next_unsent_rr_msisdn(), that is being called by
smsq_take_next_sms().

The problem is that the original function in libmsc does
allocate a 'gsm_sms' structure on heap (using talloc), while
the overwriting function did this statically, returning a
pointer to stack. This critical difference made it impossible
to spot the memleak in smsq_take_next_sms() during the
unit test execution.

Let's refactor 'sms_queue_test' to use dynamic memory allocation,
and finally fix the evil memleak in smsq_take_next_sms().

Change-Id: Iad5e4d84d8d410ea43d5907e9ddf6e5fdb55bc7a
Closes: OS#3860
changes/50/13450/5
Vadim Yanitskiy 4 years ago
parent 18f1138a6d
commit 96262a7ca6
  1. 7
      src/libmsc/sms_queue.c
  2. 39
      tests/sms_queue/sms_queue_test.c

@ -226,8 +226,13 @@ struct gsm_sms *smsq_take_next_sms(struct gsm_network *net,
osmo_strlcpy(last_msisdn, sms->dst.addr, last_msisdn_buflen);
/* Is the subscriber attached? If not, go to next SMS */
if (!sms->receiver || !sms->receiver->lu_complete)
if (!sms->receiver || !sms->receiver->lu_complete) {
LOGP(DLSMS, LOGL_DEBUG,
"Subscriber %s is not attached, skipping SMS %llu\n",
vlr_subscr_msisdn_or_name(sms->receiver), sms->id);
sms_free(sms);
continue;
}
return sms;
}

@ -26,8 +26,10 @@
#include <osmocom/msc/debug.h>
#include <osmocom/msc/vlr.h>
#include <osmocom/msc/gsm_data.h>
#include <osmocom/msc/gsm_04_11.h>
static void *talloc_ctx = NULL;
extern void *tall_gsms_ctx;
struct gsm_sms *smsq_take_next_sms(struct gsm_network *net,
char *last_msisdn,
@ -45,8 +47,6 @@ static void _test_take_next_sms_print(int i,
printf(" (last_msisdn='%s')\n", last_msisdn? last_msisdn : "NULL");
}
static struct gsm_sms fake_sms = { 0 };
struct {
const char *msisdn;
int nr_of_sms;
@ -91,11 +91,19 @@ struct gsm_sms *__wrap_db_sms_get_next_unsent_rr_msisdn(struct gsm_network *net,
const char *last_msisdn,
unsigned int max_failed)
{
static struct vlr_subscr arbitrary_vsub = { .lu_complete = true };
static struct vlr_subscr arbitrary_vsub;
struct gsm_sms *sms;
int i;
printf(" hitting database: looking for MSISDN > '%s', failed_attempts <= %d\n",
last_msisdn, max_failed);
/* Every time we call sms_free(), the internal logic of libmsc
* may call vlr_subscr_put() on our arbitrary_vsub, what would
* lead to a segfault if its use_count <= 0. To prevent this,
* let's ensure a big enough initial value. */
arbitrary_vsub.use_count = 1000;
arbitrary_vsub.lu_complete = true;
for (i = 0; i < ARRAY_SIZE(fake_sms_db); i++) {
if (!fake_sms_db[i].nr_of_sms)
continue;
@ -103,14 +111,19 @@ struct gsm_sms *__wrap_db_sms_get_next_unsent_rr_msisdn(struct gsm_network *net,
continue;
if (fake_sms_db[i].failed_attempts > max_failed)
continue;
osmo_strlcpy(fake_sms.dst.addr, fake_sms_db[i].msisdn,
sizeof(fake_sms.dst.addr));
fake_sms.receiver = fake_sms_db[i].vsub_attached? &arbitrary_vsub : NULL;
osmo_strlcpy(fake_sms.text, fake_sms_db[i].msisdn, sizeof(fake_sms.text));
sms = sms_alloc();
OSMO_ASSERT(sms);
osmo_strlcpy(sms->dst.addr, fake_sms_db[i].msisdn,
sizeof(sms->dst.addr));
sms->receiver = fake_sms_db[i].vsub_attached? &arbitrary_vsub : NULL;
osmo_strlcpy(sms->text, fake_sms_db[i].msisdn, sizeof(sms->text));
if (fake_sms_db[i].vsub_attached)
fake_sms_db[i].nr_of_sms--;
return &fake_sms;
return sms;
}
return NULL;
}
@ -127,6 +140,10 @@ void show_fake_sms_db()
printf("-->\n");
}
/* sms_free() is not safe against NULL */
#define sms_free_safe(sms) \
if (sms != NULL) sms_free(sms)
static void test_next_sms()
{
int i;
@ -141,6 +158,7 @@ static void test_next_sms()
struct gsm_sms *sms = smsq_take_next_sms(NULL, last_msisdn, sizeof(last_msisdn));
_test_take_next_sms_print(i, sms, last_msisdn);
OSMO_ASSERT(i >= 4 || sms);
sms_free_safe(sms);
}
printf("\n- SMS are pending at various nr failed attempts (cutoff at >= 10)\n");
@ -156,6 +174,7 @@ static void test_next_sms()
struct gsm_sms *sms = smsq_take_next_sms(NULL, last_msisdn, sizeof(last_msisdn));
_test_take_next_sms_print(i, sms, last_msisdn);
OSMO_ASSERT(i >= 2 || sms);
sms_free_safe(sms);
}
printf("\n- iterate the SMS DB at most once\n");
@ -206,6 +225,10 @@ int main(int argc, char **argv)
logging_ctx = talloc_named_const(talloc_ctx, 0, "logging");
osmo_init_logging2(logging_ctx, &info);
/* Share our talloc context with libmsc's GSM 04.11 code,
* so sms_alloc() would use it instead of NULL. */
tall_gsms_ctx = talloc_ctx;
OSMO_ASSERT(osmo_stderr_target);
log_set_use_color(osmo_stderr_target, 0);
log_set_print_timestamp(osmo_stderr_target, 0);

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