[PATCH] net: mac80211: Add NULL checks for sta->sdata

From: Jia-Ju Bai
Date: Mon Mar 20 2023 - 09:37:05 EST

In a previous commit 69403bad97aa, sta->sdata can be NULL, and thus it
should be checked before being used.

However, in the same call stack, sta->sdata is also used in the
following functions:

ieee80211_ba_session_work()
___ieee80211_stop_rx_ba_session(sta)
ht_dbg(sta->sdata, ...); -> No check
sdata_info(sta->sdata, ...); -> No check
ieee80211_send_delba(sta->sdata, ...) -> No check
___ieee80211_start_rx_ba_session(sta)
ht_dbg(sta->sdata, ...); -> No check
ht_dbg_ratelimited(sta->sdata, ...); -> No check
ieee80211_tx_ba_session_handle_start(sta)
sdata = sta->sdata; if (!sdata) -> Add check by previous commit
___ieee80211_stop_tx_ba_session(sdata)
ht_dbg(sta->sdata, ...); -> No check
ieee80211_start_tx_ba_cb(sdata)
sdata = sta->sdata; local = sdata->local -> No check
ieee80211_stop_tx_ba_cb(sdata)
ht_dbg(sta->sdata, ...); -> No check

Thus, to avoid possible null-pointer dereferences, the related checks
should be added.

These results are reported by a static tool designed by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
Reported-by: TOTE Robot <baijiaju@xxxxxxxxxxx>
---
net/mac80211/agg-rx.c | 68 ++++++++++++++++++++++++++-----------------
net/mac80211/agg-tx.c | 16 ++++++++--
2 files changed, 55 insertions(+), 29 deletions(-)

diff --git a/net/mac80211/agg-rx.c b/net/mac80211/agg-rx.c
index c6fa53230450..6616970785a2 100644
--- a/net/mac80211/agg-rx.c
+++ b/net/mac80211/agg-rx.c
@@ -80,19 +80,21 @@ void ___ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
RCU_INIT_POINTER(sta->ampdu_mlme.tid_rx[tid], NULL);
__clear_bit(tid, sta->ampdu_mlme.agg_session_valid);

- ht_dbg(sta->sdata,
- "Rx BA session stop requested for %pM tid %u %s reason: %d\n",
- sta->sta.addr, tid,
- initiator == WLAN_BACK_RECIPIENT ? "recipient" : "initiator",
- (int)reason);
+ if (sta->sdata) {
+ ht_dbg(sta->sdata,
+ "Rx BA session stop requested for %pM tid %u %s reason: %d\n",
+ sta->sta.addr, tid,
+ initiator == WLAN_BACK_RECIPIENT ? "recipient" : "initiator",
+ (int)reason);
+ }

- if (drv_ampdu_action(local, sta->sdata, &params))
+ if (sta->sdata && drv_ampdu_action(local, sta->sdata, &params))
sdata_info(sta->sdata,
"HW problem - can not stop rx aggregation for %pM tid %d\n",
sta->sta.addr, tid);

/* check if this is a self generated aggregation halt */
- if (initiator == WLAN_BACK_RECIPIENT && tx)
+ if (initiator == WLAN_BACK_RECIPIENT && tx && sta->sdata)
ieee80211_send_delba(sta->sdata, sta->sta.addr,
tid, WLAN_BACK_RECIPIENT, reason);

@@ -279,17 +281,21 @@ void ___ieee80211_start_rx_ba_session(struct sta_info *sta,

if (!sta->sta.deflink.ht_cap.ht_supported &&
!sta->sta.deflink.he_cap.has_he) {
- ht_dbg(sta->sdata,
- "STA %pM erroneously requests BA session on tid %d w/o HT\n",
- sta->sta.addr, tid);
+ if (sta->sdata) {
+ ht_dbg(sta->sdata,
+ "STA %pM erroneously requests BA session on tid %d w/o HT\n",
+ sta->sta.addr, tid);
+ }
/* send a response anyway, it's an error case if we get here */
goto end;
}

if (test_sta_flag(sta, WLAN_STA_BLOCK_BA)) {
- ht_dbg(sta->sdata,
- "Suspend in progress - Denying ADDBA request (%pM tid %d)\n",
- sta->sta.addr, tid);
+ if (sta->sdata) {
+ ht_dbg(sta->sdata,
+ "Suspend in progress - Denying ADDBA request (%pM tid %d)\n",
+ sta->sta.addr, tid);
+ }
goto end;
}

@@ -322,8 +328,10 @@ void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
buf_size = sta->sta.max_rx_aggregation_subframes;
params.buf_size = buf_size;

- ht_dbg(sta->sdata, "AddBA Req buf_size=%d for %pM\n",
- buf_size, sta->sta.addr);
+ if (sta->sdata) {
+ ht_dbg(sta->sdata, "AddBA Req buf_size=%d for %pM\n",
+ buf_size, sta->sta.addr);
+ }

/* examine state machine */
lockdep_assert_held(&sta->ampdu_mlme.mtx);
@@ -332,9 +340,11 @@ void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
if (sta->ampdu_mlme.tid_rx_token[tid] == dialog_token) {
struct tid_ampdu_rx *tid_rx;

- ht_dbg_ratelimited(sta->sdata,
- "updated AddBA Req from %pM on tid %u\n",
- sta->sta.addr, tid);
+ if (sta->sdata) {
+ ht_dbg_ratelimited(sta->sdata,
+ "updated AddBA Req from %pM on tid %u\n",
+ sta->sta.addr, tid);
+ }
/* We have no API to update the timeout value in the
* driver so reject the timeout update if the timeout
* changed. If it did not change, i.e., no real update,
@@ -350,9 +360,11 @@ void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
goto end;
}

- ht_dbg_ratelimited(sta->sdata,
- "unexpected AddBA Req from %pM on tid %u\n",
- sta->sta.addr, tid);
+ if (sta->sdata) {
+ ht_dbg_ratelimited(sta->sdata,
+ "unexpected AddBA Req from %pM on tid %u\n",
+ sta->sta.addr, tid);
+ }

/* delete existing Rx BA session on the same tid */
___ieee80211_stop_rx_ba_session(sta, tid, WLAN_BACK_RECIPIENT,
@@ -362,9 +374,11 @@ void ___ieee80211_start_rx_ba_session(struct sta_info *sta,

if (ieee80211_hw_check(&local->hw, SUPPORTS_REORDERING_BUFFER)) {
ret = drv_ampdu_action(local, sta->sdata, &params);
- ht_dbg(sta->sdata,
- "Rx A-MPDU request on %pM tid %d result %d\n",
- sta->sta.addr, tid, ret);
+ if (sta->sdata) {
+ ht_dbg(sta->sdata,
+ "Rx A-MPDU request on %pM tid %d result %d\n",
+ sta->sta.addr, tid, ret);
+ }
if (!ret)
status = WLAN_STATUS_SUCCESS;
goto end;
@@ -401,8 +415,10 @@ void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
__skb_queue_head_init(&tid_agg_rx->reorder_buf[i]);

ret = drv_ampdu_action(local, sta->sdata, &params);
- ht_dbg(sta->sdata, "Rx A-MPDU request on %pM tid %d result %d\n",
- sta->sta.addr, tid, ret);
+ if (sta->sdata) {
+ ht_dbg(sta->sdata, "Rx A-MPDU request on %pM tid %d result %d\n",
+ sta->sta.addr, tid, ret);
+ }
if (ret) {
kfree(tid_agg_rx->reorder_buf);
kfree(tid_agg_rx->reorder_time);
diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
index f9514bacbd4a..03b31b6e7ac7 100644
--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -368,8 +368,10 @@ int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid,

spin_unlock_bh(&sta->lock);

- ht_dbg(sta->sdata, "Tx BA session stop requested for %pM tid %u\n",
- sta->sta.addr, tid);
+ if (sta->sdata) {
+ ht_dbg(sta->sdata, "Tx BA session stop requested for %pM tid %u\n",
+ sta->sta.addr, tid);
+ }

del_timer_sync(&tid_tx->addba_resp_timer);
del_timer_sync(&tid_tx->session_timer);
@@ -776,7 +778,12 @@ void ieee80211_start_tx_ba_cb(struct sta_info *sta, int tid,
struct tid_ampdu_tx *tid_tx)
{
struct ieee80211_sub_if_data *sdata = sta->sdata;
- struct ieee80211_local *local = sdata->local;
+ struct ieee80211_local *local;
+
+ if (!sdata)
+ return;
+
+ local = sdata->local;

if (WARN_ON(test_and_set_bit(HT_AGG_STATE_DRV_READY, &tid_tx->state)))
return;
@@ -902,6 +909,9 @@ void ieee80211_stop_tx_ba_cb(struct sta_info *sta, int tid,
bool send_delba = false;
bool start_txq = false;

+ if (!sdata)
+ return;
+
ht_dbg(sdata, "Stopping Tx BA session for %pM tid %d\n",
sta->sta.addr, tid);

--
2.34.1