FAILED: patch "[PATCH] wifi: mac80211: refuse to make a monitor active when it has" failed to apply to 5.15-stable tree

PATCH New [email protected] 2 participants 3 messages Sep 22 – Sep 23

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Stable branch mac80211

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[email protected]

author maintainer

2026-09-22 15:12 UTC #0 lore raw

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 2b04d6556964ae9f89819b86a0a7801e39c3aae5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026092224-dawdler-equator-70f2@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2b04d6556964ae9f89819b86a0a7801e39c3aae5 Mon Sep 17 00:00:00 2001
From: Devin Wittmayer <[email protected]>
Date: Fri, 4 Sep 2026 13:03:38 -0700
Subject: [PATCH] wifi: mac80211: refuse to make a monitor active when it has
no queue

A monitor interface only gets a TXQ if it's created active, and one can't be added later. Setting the flag on a down interface is still allowed, so the driver is handed a monitor with no queue. ath9k dereferences it:

  BUG: kernel NULL pointer dereference, address: 0000000000000066
  RIP: 0010:ath_tx_node_init+0x49/0x170 [ath9k]
   ath9k_add_interface+0x10c/0x140 [ath9k]
   drv_add_interface+0x54/0x250 [mac80211]
   ieee80211_do_open+0x32f/0x800 [mac80211]

Reached with CAP_NET_ADMIN by "iw dev X set monitor active" followed by "ip link set X up". RTNL is held, so netlink operations block behind it.

Refuse the flag when there is no queue to give.

Fixes 79af1f866193 ("mac80211: avoid allocating TXQs that won't be used")

Cc [email protected]

Signed-off-by Devin Wittmayer <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Johannes Berg <[email protected]>

net/mac80211/cfg.c +4 -0

index d3558f0c7550..a1753335eb9d 100644
@@ -115,6 +115,10 @@ static int ieee80211_set_mon_options(struct ieee80211_sub_if_data *sdata,
 			return -EBUSY;
 	}
 
+	/* TXQs are reserved in ieee80211_if_add() and cannot be added later */
+	if ((params->flags & MONITOR_FLAG_ACTIVE) && !sdata->vif.txq)
+		return -EOPNOTSUPP;
+
 	/* validate whether MU-MIMO can be configured */
 	if (!ieee80211_hw_check(&local->hw, WANT_MONITOR_VIF) &&
 	    !ieee80211_hw_check(&local->hw, NO_VIRTUAL_MONITOR) &&

Sasha Levin

maintainer

2026-09-23 02:16 UTC #1 lore raw

PATCH 1/2 wifi: mac80211: track MU-MIMO configuration on disabled interfaces

From: Benjamin Berg <[email protected]>

[ Upstream commit a5aa46f1ac4f53e03b9b75cbf55634131f2f8cac ]

For monitoring, userspace will try to configure the VIF sdata, while the driver may see the monitor_sdata that is created when only monitor interfaces are up. This causes the odd situation that it may not be possible to store the MU-MIMO configuration on monitor_sdata.

Fix this by storing that information on the VIF sdata and updating the monitor_sdata when available and the interface is up. Also, adjust the code that adds monitor_sdata so that it will configure MU-MIMO based on the newly added interface or one of the existing ones.

This should give a mostly consistent behaviour when configuring MU-MIMO on sniffer interfaces. Should the user configure MU-MIMO on multiple sniffer interfaces, then mac80211 will simply select one of the configurations. This behaviour should be good enough and avoids breaking user expectations in the common scenarios.

Signed-off-by Benjamin Berg <[email protected]>

Reviewed-by Johannes Berg <[email protected]>

Signed-off-by Miri Korenblit <[email protected]>

Link https://patch.msgid.link/20251110141514.677915f8f6bb.If4e04a57052f9ca763562a67248b06fd80d0c2c1@changeid open here

Signed-off-by Johannes Berg <[email protected]>

Backport adaptation for 5.15, as a dependency of 2b04d6556964 ("wifi: mac80211: refuse to make a monitor active when it has no queue"):

Use vif.mu_mimo_owner and ieee80211_bss_info_change_notify() instead of the newer link-specific state and notification API. Gate MU-MIMO support on WANT_MONITOR_VIF; this tree has no NO_VIRTUAL_MONITOR mode. Preserve its cooked-monitor checks and existing monitor accounting.

Use u.mntr.list to walk this tree's monitor list. Pass the creator when opening a monitor, and select an existing configuration when stopping an interface or reconfiguring hardware. Update the existing wake_up call in ieee80211_reconfig() instead of adding the newer, relocated call site. No new functions are introduced.

Stable-dep-of: 2b04d6556964 ("wifi: mac80211: refuse to make a monitor active when it has no queue")

Signed-off-by Sasha Levin <[email protected]>

---
 net/mac80211/cfg.c         | 37 +++++++++++++++++++++++++--------
 net/mac80211/ieee80211_i.h |  3 ++-
 net/mac80211/iface.c       | 42 ++++++++++++++++++++++++++++++++------
 net/mac80211/util.c        |  3 ++-
 4 files changed, 68 insertions(+), 17 deletions(-)

net/mac80211/cfg.c +28 -9

index 706ff67f4254a..c019dd9af6866 100644
@@ -39,11 +39,14 @@ static void ieee80211_set_mu_mimo_follow(struct ieee80211_sub_if_data *sdata,
 		memcpy(sdata->vif.bss_conf.mu_group.position,
 		       params->vht_mumimo_groups + WLAN_MEMBERSHIP_LEN,
 		       WLAN_USER_POSITION_LEN);
-		ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_MU_GROUPS);
+
 		/* don't care about endianness - just check for 0 */
 		memcpy(&membership, params->vht_mumimo_groups,
 		       WLAN_MEMBERSHIP_LEN);
 		mu_mimo_groups = membership != 0;
+
+		/* Unset following if configured explicitly */
+		eth_broadcast_addr(sdata->u.mntr.mu_follow_addr);
 	}
 
 	if (params->vht_mumimo_follow_addr) {

@@ -51,16 +54,25 @@ static void ieee80211_set_mu_mimo_follow(struct ieee80211_sub_if_data *sdata,
 			is_valid_ether_addr(params->vht_mumimo_follow_addr);
 		ether_addr_copy(sdata->u.mntr.mu_follow_addr,
 				params->vht_mumimo_follow_addr);
+
+		/* Unset current membership until a management frame is RXed */
+		memset(sdata->vif.bss_conf.mu_group.membership, 0,
+		       WLAN_MEMBERSHIP_LEN);
 	}
 
 	sdata->vif.mu_mimo_owner = mu_mimo_groups || mu_mimo_follow;
+
+	/* Notify only after setting mu_mimo_owner */
+	if (sdata->vif.mu_mimo_owner &&
+	    sdata->flags & IEEE80211_SDATA_IN_DRIVER)
+		ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_MU_GROUPS);
 }
 
 static int ieee80211_set_mon_options(struct ieee80211_sub_if_data *sdata,
 				     struct vif_params *params)
 {
 	struct ieee80211_local *local = sdata->local;
-	struct ieee80211_sub_if_data *monitor_sdata;
+	struct ieee80211_sub_if_data *monitor_sdata = NULL;
 
 	/* check flags first */
 	if (params->flags && ieee80211_sdata_running(sdata)) {

@@ -79,18 +91,25 @@ static int ieee80211_set_mon_options(struct ieee80211_sub_if_data *sdata,
 			return -EBUSY;
 	}
 
-	/* also validate MU-MIMO change */
-	monitor_sdata = wiphy_dereference(local->hw.wiphy,
-					  local->monitor_sdata);
-
-	if (!monitor_sdata &&
+	/* validate whether MU-MIMO can be configured */
+	if (!ieee80211_hw_check(&local->hw, WANT_MONITOR_VIF) &&
 	    (params->vht_mumimo_groups || params->vht_mumimo_follow_addr))
 		return -EOPNOTSUPP;
 
+	/* Also update dependent monitor_sdata if required */
+	if (test_bit(SDATA_STATE_RUNNING, &sdata->state))
+		monitor_sdata = wiphy_dereference(local->hw.wiphy,
+						  local->monitor_sdata);
+
 	/* apply all changes now - no failures allowed */
 
-	if (monitor_sdata)
-		ieee80211_set_mu_mimo_follow(monitor_sdata, params);
+	if (ieee80211_hw_check(&local->hw, WANT_MONITOR_VIF)) {
+		/* This is copied in when the VIF is activated */
+		ieee80211_set_mu_mimo_follow(sdata, params);
+
+		if (monitor_sdata)
+			ieee80211_set_mu_mimo_follow(monitor_sdata, params);
+	}
 
 	if (params->flags) {
 		if (ieee80211_sdata_running(sdata)) {

net/mac80211/ieee80211_i.h +2 -1

index 306359d435717..a168e52d63c9c 100644
@@ -1963,7 +1963,8 @@ void ieee80211_adjust_monitor_flags(struct ieee80211_sub_if_data *sdata,
 				    const int offset);
 int ieee80211_do_open(struct wireless_dev *wdev, bool coming_up);
 void ieee80211_sdata_stop(struct ieee80211_sub_if_data *sdata);
-int ieee80211_add_virtual_monitor(struct ieee80211_local *local);
+int ieee80211_add_virtual_monitor(struct ieee80211_local *local,
+				  struct ieee80211_sub_if_data *creator_sdata);
 void ieee80211_del_virtual_monitor(struct ieee80211_local *local);
 
 bool __ieee80211_recalc_txpower(struct ieee80211_sub_if_data *sdata);

net/mac80211/iface.c +36 -6

73 lines not on this page · raw message

net/mac80211/util.c +2 -1

index 5b1799dfa6757..6ea8a14fbf6c2 100644
@@ -2634,8 +2634,9 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 
  wake_up:
 
+	/* Passing NULL means an interface is picked for configuration */
 	if (local->monitors == local->open_count && local->monitors > 0)
-		ieee80211_add_virtual_monitor(local);
+		ieee80211_add_virtual_monitor(local, NULL);
 
 	/*
 	 * Clear the WLAN_STA_BLOCK_BA flag so new aggregation

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-09-23 02:16 UTC #2 lore raw

PATCH 2/2 wifi: mac80211: refuse to make a monitor active when it has no queue

From: Devin Wittmayer <[email protected]>

[ Upstream commit 2b04d6556964ae9f89819b86a0a7801e39c3aae5 ]

  BUG: kernel NULL pointer dereference, address: 0000000000000066
  RIP: 0010:ath_tx_node_init+0x49/0x170 [ath9k]
   ath9k_add_interface+0x10c/0x140 [ath9k]
   drv_add_interface+0x54/0x250 [mac80211]
   ieee80211_do_open+0x32f/0x800 [mac80211]

Reached with CAP_NET_ADMIN by "iw dev X set monitor active" followed by "ip link set X up". RTNL is held, so netlink operations block behind it.

Refuse the flag when there is no queue to give.

Fixes 79af1f866193 ("mac80211: avoid allocating TXQs that won't be used")

Cc [email protected]

Signed-off-by Devin Wittmayer <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Johannes Berg <[email protected]>

Signed-off-by Sasha Levin <[email protected]>

---
 net/mac80211/cfg.c | 4 ++++
 1 file changed, 4 insertions(+)

net/mac80211/cfg.c +4 -0

index c019dd9af6866..514ac12414aed 100644
@@ -91,6 +91,10 @@ static int ieee80211_set_mon_options(struct ieee80211_sub_if_data *sdata,
 			return -EBUSY;
 	}
 
+	/* TXQs are reserved in ieee80211_if_add() and cannot be added later */
+	if ((params->flags & MONITOR_FLAG_ACTIVE) && !sdata->vif.txq)
+		return -EOPNOTSUPP;
+
 	/* validate whether MU-MIMO can be configured */
 	if (!ieee80211_hw_check(&local->hw, WANT_MONITOR_VIF) &&
 	    (params->vht_mumimo_groups || params->vht_mumimo_follow_addr))

Signature · 1 line

2.53.0