Commit b3e50e04 authored Nov 29, 2021 by Brian Norris Committed by Greg Kroah-Hartman Jan 27, 2022

mwifiex: Fix possible ABBA deadlock



[ Upstream commit 1b8bb8919ef81bfc8873d223b9361f1685f2106d ]

Quoting Jia-Ju Bai <baijiaju1990@gmail.com>:

  mwifiex_dequeue_tx_packet()
     spin_lock_bh(&priv->wmm.ra_list_spinlock); --> Line 1432 (Lock A)
     mwifiex_send_addba()
       spin_lock_bh(&priv->sta_list_spinlock); --> Line 608 (Lock B)

  mwifiex_process_sta_tx_pause()
     spin_lock_bh(&priv->sta_list_spinlock); --> Line 398 (Lock B)
     mwifiex_update_ralist_tx_pause()
       spin_lock_bh(&priv->wmm.ra_list_spinlock); --> Line 941 (Lock A)

Similar report for mwifiex_process_uap_tx_pause().

While the locking expectations in this driver are a bit unclear, the
Fixed commit only intended to protect the sta_ptr, so we can drop the
lock as soon as we're done with it.

IIUC, this deadlock cannot actually happen, because command event
processing (which calls mwifiex_process_sta_tx_pause()) is
sequentialized with TX packet processing (e.g.,
mwifiex_dequeue_tx_packet()) via the main loop (mwifiex_main_process()).
But it's good not to leave this potential issue lurking.

Fixes: f0f7c227 ("mwifiex: minor cleanups w/ sta_list_spinlock in cfg80211.c")
Cc: Douglas Anderson <dianders@chromium.org>
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Link: https://lore.kernel.org/linux-wireless/0e495b14-efbb-e0da-37bd-af6bd677ee2c@gmail.com/


Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/YaV0pllJ5p/EuUat@google.com


Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 236399a6

drivers/net/wireless/marvell/mwifiex/sta_event.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -364,12 +364,14 @@ static void mwifiex_process_uap_tx_pause(struct mwifiex_private *priv,
		sta_ptr = mwifiex_get_sta_entry(priv, tp->peermac);
		if (sta_ptr && sta_ptr->tx_pause != tp->tx_pause) {
		sta_ptr->tx_pause = tp->tx_pause;
		spin_unlock_bh(&priv->sta_list_spinlock);
		mwifiex_update_ralist_tx_pause(priv, tp->peermac,
		tp->tx_pause);
		}
		} else {
		spin_unlock_bh(&priv->sta_list_spinlock);
		}
		}
		}

		static void mwifiex_process_sta_tx_pause(struct mwifiex_private *priv,
		struct mwifiex_ie_types_header *tlv)
		@@ -399,14 +401,16 @@ static void mwifiex_process_sta_tx_pause(struct mwifiex_private *priv,
		sta_ptr = mwifiex_get_sta_entry(priv, tp->peermac);
		if (sta_ptr && sta_ptr->tx_pause != tp->tx_pause) {
		sta_ptr->tx_pause = tp->tx_pause;
		spin_unlock_bh(&priv->sta_list_spinlock);
		mwifiex_update_ralist_tx_pause(priv,
		tp->peermac,
		tp->tx_pause);
		}
		} else {
		spin_unlock_bh(&priv->sta_list_spinlock);
		}
		}
		}
		}

		void mwifiex_process_multi_chan_event(struct mwifiex_private *priv,
		struct sk_buff *event_skb)