pdch: Fix heap-use-after-free in pdch->ulc
In existing previous code, pdch->ulc would be freed in
gprs_rlcmac_pdch::free_resources() when it became disabled as per PCUIF
info_ind (for instance, when a DYN TS is switched PDCH->SDCCH8).
However, pdch->ulc was so far only allocated during pdch_init, which is
only called during bts_alloc() time.
Hence, after first info_ind disabling it, if it became again enabled
(again by info_ind re-enabling it after SDCCH8 was not longer in use),
the pdch->ulc would be used again but it would point to freed memory.
Let's rearrange how/when resources are freed to make it more logical.
With this patch, pdch internal resources are freed upon ->disable(), and
re-allocated upon ->enable().
Change-Id: Id51f5f6a54ac9f24b784c17bc360ac38f5726fc7
diff --git a/src/osmobts_sock.c b/src/osmobts_sock.c
index 5c6415f..91b62a0 100644
--- a/src/osmobts_sock.c
+++ b/src/osmobts_sock.c
@@ -121,7 +121,8 @@
}
#endif
for (ts = 0; ts < 8; ts++)
- pdch_disable(&bts->trx[trx].pdch[ts]);
+ if (pdch_is_enabled(&bts->trx[trx].pdch[ts]))
+ pdch_disable(&bts->trx[trx].pdch[ts]);
/* FIXME: NOT ALL RESOURCES are freed in this case... inconsistent with the other code. Share the code with pcu_l1if.c
for the reset. */
bts_trx_free_all_tbf(&bts->trx[trx]);
diff --git a/src/pcu_l1_if.cpp b/src/pcu_l1_if.cpp
index 2373f60..5aa8849 100644
--- a/src/pcu_l1_if.cpp
+++ b/src/pcu_l1_if.cpp
@@ -650,7 +650,7 @@
for (trx_nr = 0; trx_nr < ARRAY_SIZE(bts->trx); trx_nr++) {
bts->trx[trx_nr].arfcn = info_ind->trx[trx_nr].arfcn;
for (ts_nr = 0; ts_nr < ARRAY_SIZE(bts->trx[0].pdch); ts_nr++)
- bts->trx[trx_nr].pdch[ts_nr].free_resources();
+ bts->trx[trx_nr].pdch[ts_nr].disable();
}
gprs_bssgp_destroy(bts);
exit(0);
@@ -818,7 +818,6 @@
} else {
if (pdch->is_enabled()) {
pcu_tx_act_req(bts, pdch, 0);
- pdch->free_resources();
pdch->disable();
}
}
diff --git a/src/pdch.cpp b/src/pdch.cpp
index 9321384..2ec40ce 100644
--- a/src/pdch.cpp
+++ b/src/pdch.cpp
@@ -139,19 +139,24 @@
/* Initialize the PTCCH/D message (Packet Timing Advance Control Channel) */
memset(pdch->ptcch_msg, PTCCH_TAI_FREE, PTCCH_TAI_NUM);
memset(pdch->ptcch_msg + PTCCH_TAI_NUM, PTCCH_PADDING, 7);
- pdch->ulc = pdch_ulc_alloc(pdch, trx->bts);
}
void gprs_rlcmac_pdch::enable()
{
- /* TODO: Check if there are still allocated resources.. */
+ OSMO_ASSERT(m_is_enabled == 0);
INIT_LLIST_HEAD(&paging_list);
+
+ OSMO_ASSERT(!this->ulc);
+ this->ulc = pdch_ulc_alloc(this, trx->bts);
+
m_is_enabled = 1;
}
void gprs_rlcmac_pdch::disable()
{
- /* TODO.. kick free_resources once we know the TRX/TS we are on */
+ OSMO_ASSERT(m_is_enabled == 1);
+ this->free_resources();
+
m_is_enabled = 0;
}
@@ -159,10 +164,6 @@
{
struct gprs_rlcmac_paging *pag;
- /* we are not enabled. there should be no resources */
- if (!is_enabled())
- return;
-
/* kick all TBF on slot */
pdch_free_all_tbf(this);
@@ -171,6 +172,7 @@
talloc_free(pag);
talloc_free(this->ulc);
+ this->ulc = NULL;
}
struct gprs_rlcmac_paging *gprs_rlcmac_pdch::dequeue_paging()
@@ -1174,6 +1176,12 @@
}
}
-void pdch_disable(struct gprs_rlcmac_pdch *pdch) {
+void pdch_disable(struct gprs_rlcmac_pdch *pdch)
+{
pdch->disable();
}
+
+bool pdch_is_enabled(const struct gprs_rlcmac_pdch *pdch)
+{
+ return pdch->is_enabled();
+}
diff --git a/src/pdch.h b/src/pdch.h
index cfa0195..00f0b9d 100644
--- a/src/pdch.h
+++ b/src/pdch.h
@@ -55,8 +55,6 @@
bool add_paging(uint8_t chan_needed, const struct osmo_mobile_identity *mi);
- void free_resources();
-
bool is_enabled() const;
void enable();
@@ -145,6 +143,8 @@
enum gprs_rlcmac_tbf_direction dir);
gprs_rlcmac_tbf *tbf_by_tfi(uint8_t tfi,
enum gprs_rlcmac_tbf_direction dir);
+
+ void free_resources();
#endif
uint8_t m_num_tbfs[2];
@@ -191,6 +191,7 @@
void pdch_init(struct gprs_rlcmac_pdch *pdch, struct gprs_rlcmac_trx *trx, uint8_t ts_nr);
void pdch_free_all_tbf(struct gprs_rlcmac_pdch *pdch);
void pdch_disable(struct gprs_rlcmac_pdch *pdch);
+bool pdch_is_enabled(const struct gprs_rlcmac_pdch *pdch);
#ifdef __cplusplus
}
#endif
diff --git a/tests/tbf/TbfTest.cpp b/tests/tbf/TbfTest.cpp
index 2c2c7ae..5065e90 100644
--- a/tests/tbf/TbfTest.cpp
+++ b/tests/tbf/TbfTest.cpp
@@ -2282,7 +2282,7 @@
the_pcu->alloc_algorithm = alloc_algorithm_b;
bts->trx[0].pdch[2].enable();
bts->trx[0].pdch[3].enable();
- bts->trx[0].pdch[4].enable();
+ /* bts->trx[0].pdch[4].enable(); Already enabled during setup_bts() */
bts->trx[0].pdch[5].enable();
gprs_bssgp_init(bts, 4234, 4234, 1, 1, false, 0, 0, 0);
@@ -2327,7 +2327,7 @@
the_pcu->alloc_algorithm = alloc_algorithm_b;
bts->trx[0].pdch[2].enable();
bts->trx[0].pdch[3].enable();
- bts->trx[0].pdch[4].enable();
+ /* bts->trx[0].pdch[4].enable(); Already enabled during setup_bts()) */
bts->trx[0].pdch[5].enable();
gprs_bssgp_init(bts, 5234, 5234, 1, 1, false, 0, 0, 0);
diff --git a/tests/ulc/PdchUlcTest.cpp b/tests/ulc/PdchUlcTest.cpp
index c980e33..3547bf6 100644
--- a/tests/ulc/PdchUlcTest.cpp
+++ b/tests/ulc/PdchUlcTest.cpp
@@ -49,11 +49,19 @@
}
}
+static struct gprs_rlcmac_bts *setup_new_bts(void)
+{
+ struct gprs_rlcmac_bts *bts = bts_alloc(the_pcu, 0);
+ struct gprs_rlcmac_pdch *pdch = &bts->trx[0].pdch[0];
+ pdch->enable();
+ return bts;
+}
+
static void test_reserve_multiple()
{
printf("=== start: %s ===\n", __FUNCTION__);
const uint32_t fn = 20;
- struct gprs_rlcmac_bts *bts = bts_alloc(the_pcu, 0);
+ struct gprs_rlcmac_bts *bts = setup_new_bts();
struct gprs_rlcmac_pdch *pdch = &bts->trx[0].pdch[0];
struct gprs_rlcmac_tbf *tbf1 = (struct gprs_rlcmac_tbf*)0x1234; /*Dummy pointer */
struct gprs_rlcmac_tbf *tbf2 = (struct gprs_rlcmac_tbf*)0x5678; /*Dummy pointer */
@@ -172,7 +180,7 @@
the_pcu->alloc_algorithm = _alloc_algorithm_dummy;
- struct gprs_rlcmac_bts *bts = bts_alloc(the_pcu, 0);
+ struct gprs_rlcmac_bts *bts = setup_new_bts();
struct GprsMs *ms = ms_alloc(bts, 0x12345678);
struct gprs_rlcmac_tbf *tbf1 = tbf_alloc_dl_tbf(bts, ms, 0, true);
struct gprs_rlcmac_pdch *pdch = &tbf1->trx->pdch[0];
@@ -215,7 +223,7 @@
static void test_next_free_fn_sba()
{
printf("=== start: %s ===\n", __FUNCTION__);
- struct gprs_rlcmac_bts *bts = bts_alloc(the_pcu, 0);
+ struct gprs_rlcmac_bts *bts = setup_new_bts();
struct gprs_rlcmac_pdch *pdch = &bts->trx[0].pdch[0];
struct gprs_rlcmac_sba *sba1, *sba2, *sba3, *sba4;
@@ -239,7 +247,7 @@
static void test_next_free_fn_rrbp()
{
printf("=== start: %s ===\n", __FUNCTION__);
- struct gprs_rlcmac_bts *bts = bts_alloc(the_pcu, 0);
+ struct gprs_rlcmac_bts *bts = setup_new_bts();
struct gprs_rlcmac_pdch *pdch = &bts->trx[0].pdch[0];
struct gprs_rlcmac_sba *sba1;
uint32_t poll_fn, curr_fn;