[PATCH 4.13 106/109] mac80211: fix deadlock in driver-managed RX BA session start

Greg Kroah-Hartman
2017-09-24T20:45:03Z

From: Johannes Berg <johannes.berg@intel.com>

commit bde59c475e0883e4c4294bcd9b9c7e08ae18c828 upstream.

When an RX BA session is started by the driver, and it has to tell
mac80211 about it, the corresponding bit in tid_rx_manage_offl gets
set and the BA session work is scheduled. Upon testing this bit, it
will call __ieee80211_start_rx_ba_session(), thus deadlocking as it
already holds the ampdu_mlme.mtx, which that acquires again.

Fix this by adding ___ieee80211_start_rx_ba_session(), a version of
the function that requires the mutex already held.

Fixes: 699cb58c8a52 ("mac80211: manage RX BA session offload without SKB queue")
Reported-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/mac80211/agg-rx.c | 32 +++++++++++++++++++++-----------
net/mac80211/ht.c | 6 +++---
net/mac80211/ieee80211_i.h | 4 ++++
3 files changed, 28 insertions(+), 14 deletions(-)

--- a/net/mac80211/agg-rx.c
+++ b/net/mac80211/agg-rx.c
@@ -245,10 +245,10 @@ static void ieee80211_send_addba_resp(st
ieee80211_tx_skb(sdata, skb);
}

-void __ieee80211_start_rx_ba_session(struct sta_info *sta,
- u8 dialog_token, u16 timeout,
- u16 start_seq_num, u16 ba_policy, u16 tid,
- u16 buf_size, bool tx, bool auto_seq)
+void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
+ u8 dialog_token, u16 timeout,
+ u16 start_seq_num, u16 ba_policy, u16 tid,
+ u16 buf_size, bool tx, bool auto_seq)
{
struct ieee80211_local *local = sta->sdata->local;
struct tid_ampdu_rx *tid_agg_rx;
@@ -267,7 +267,7 @@ void __ieee80211_start_rx_ba_session(str
ht_dbg(sta->sdata,
"STA %pM requests BA session on unsupported tid %d\n",
sta->sta.addr, tid);
- goto end_no_lock;
+ goto end;
}

if (!sta->sta.ht_cap.ht_supported) {
@@ -275,14 +275,14 @@ void __ieee80211_start_rx_ba_session(str
"STA %pM erroneously requests BA session on tid %d w/o QoS\n",
sta->sta.addr, tid);
/* send a response anyway, it's an error case if we get here */
- goto end_no_lock;
+ 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);
- goto end_no_lock;
+ goto end;
}

/* sanity check for incoming parameters:
@@ -296,7 +296,7 @@ void __ieee80211_start_rx_ba_session(str
ht_dbg_ratelimited(sta->sdata,
"AddBA Req with bad params from %pM on tid %u. policy %d, buffer size %d\n",
sta->sta.addr, tid, ba_policy, buf_size);
- goto end_no_lock;
+ goto end;
}
/* determine default buffer size */
if (buf_size == 0)
@@ -311,7 +311,7 @@ void __ieee80211_start_rx_ba_session(str
buf_size, sta->sta.addr);

/* examine state machine */
- mutex_lock(&sta->ampdu_mlme.mtx);
+ lockdep_assert_held(&sta->ampdu_mlme.mtx);

if (test_bit(tid, sta->ampdu_mlme.agg_session_valid)) {
if (sta->ampdu_mlme.tid_rx_token[tid] == dialog_token) {
@@ -415,15 +415,25 @@ end:
__clear_bit(tid, sta->ampdu_mlme.unexpected_agg);
sta->ampdu_mlme.tid_rx_token[tid] = dialog_token;
}
- mutex_unlock(&sta->ampdu_mlme.mtx);

-end_no_lock:
if (tx)
ieee80211_send_addba_resp(sta->sdata, sta->sta.addr, tid,
dialog_token, status, 1, buf_size,
timeout);
}

+void __ieee80211_start_rx_ba_session(struct sta_info *sta,
+ u8 dialog_token, u16 timeout,
+ u16 start_seq_num, u16 ba_policy, u16 tid,
+ u16 buf_size, bool tx, bool auto_seq)
+{
+ mutex_lock(&sta->ampdu_mlme.mtx);
+ ___ieee80211_start_rx_ba_session(sta, dialog_token, timeout,
+ start_seq_num, ba_policy, tid,
+ buf_size, tx, auto_seq);
+ mutex_unlock(&sta->ampdu_mlme.mtx);
+}
+
void ieee80211_process_addba_request(struct ieee80211_local *local,
struct sta_info *sta,
struct ieee80211_mgmt *mgmt,
--- a/net/mac80211/ht.c
+++ b/net/mac80211/ht.c
@@ -333,9 +333,9 @@ void ieee80211_ba_session_work(struct wo

if (test_and_clear_bit(tid,
sta->ampdu_mlme.tid_rx_manage_offl))
- __ieee80211_start_rx_ba_session(sta, 0, 0, 0, 1, tid,
- IEEE80211_MAX_AMPDU_BUF,
- false, true);
+ ___ieee80211_start_rx_ba_session(sta, 0, 0, 0, 1, tid,
+ IEEE80211_MAX_AMPDU_BUF,
+ false, true);

if (test_and_clear_bit(tid + IEEE80211_NUM_TIDS,
sta->ampdu_mlme.tid_rx_manage_offl))
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1760,6 +1760,10 @@ void __ieee80211_start_rx_ba_session(str
u8 dialog_token, u16 timeout,
u16 start_seq_num, u16 ba_policy, u16 tid,
u16 buf_size, bool tx, bool auto_seq);
+void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
+ u8 dialog_token, u16 timeout,
+ u16 start_seq_num, u16 ba_policy, u16 tid,
+ u16 buf_size, bool tx, bool auto_seq);
void ieee80211_sta_tear_down_BA_sessions(struct sta_info *sta,
enum ieee80211_agg_stop_reason reason);
void ieee80211_process_delba(struct ieee80211_sub_if_data *sdata,