From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 453B127B4F7; Mon, 17 Aug 2026 14:22:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786976575; cv=none; b=HjUc60gjJuBD2zg3XkYNA8MrBCBbDORvnsUejjKcZWO5wl6PZzY3CvDyubybvqrNIthW7bLFqX7OloUYZUPuFuPRb3eo01knS2aYR1lR/Hq4dNwflGcb+pYDkkYk/YPy4r0E3JDYQB+xcOkkfLRdJr1/u2R36sqC3x5jK8CfguQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786976575; c=relaxed/simple; bh=TcguYLkvmg67Kmf9W1m5Dqz1zGjdgnJ8ORiAghcaETM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hiHCUnLMhPNalOAhTCDKo7/3Uu+CRqoii0W0HCYNgkX6RGux5A8tjv4KM8KGyFlJMMvdIkvn8B2Mnt8mAAWqx3Qh81YRc96wvwXRIsUP0l3AZ83VNQqjevsxRDhuJ9LaSWd/vk860JlueDUYJUl1JzBe2uUn8mHZ79TVNF8b27w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=lujlkyUC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="lujlkyUC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DEDE1F00A3A; Mon, 17 Aug 2026 14:22:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786976574; bh=O568R7y3JFrWjeNkhSZ7SwXwSNQjp/1qjJc8PSeYfs8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=lujlkyUCuJ/k6C9UUmNI2KPBA3PCnhB0LWtieRWyEJKag2amYnmFIlujcW4pJImcT raqgXwXy4iWDDFc2znGllLwmvGHfEgGO53ydB91UTUaRiKNYYpEsbBn5xyUIuO1oVY fbGSNZHOFdo/czxf+0nfqPjzZYNoUfdJnxQyirq0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Cen Zhang , Johannes Berg , Sasha Levin Subject: [PATCH 5.15 031/456] wifi: mac80211: free AP_VLAN bc_buf SKBs outside IRQ lock Date: Mon, 17 Aug 2026 15:27:01 +0200 Message-ID: <20260817132541.221618905@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132539.792407575@linuxfoundation.org> References: <20260817132539.792407575@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cen Zhang [ Upstream commit f3858d5b1432098c1936e03d6e03dd0e33facf60 ] ieee80211_do_stop() removes AP_VLAN packets from the parent AP ps->bc_buf while holding ps->bc_buf.lock with IRQs disabled. It then calls ieee80211_free_txskb() before dropping the lock. ieee80211_free_txskb() is not just a passive SKB release. For SKBs with TX status state it can report a dropped frame through cfg80211/nl80211, and that path can reach netlink tap transmit. This is the same reason the pending queue cleanup in ieee80211_do_stop() already unlinks SKBs under the queue lock and frees them after IRQ state is restored. The buggy scenario involves two paths, with each column showing the order within that path: AP_VLAN management TX: AP_VLAN stop: 1. attach ACK-status state 1. clear the running state 2. queue a multicast SKB on 2. take ps->bc_buf.lock with IRQs parent ps->bc_buf disabled 3. unlink the AP_VLAN SKB 4. call ieee80211_free_txskb() Unlink matching AP_VLAN SKBs from ps->bc_buf under the existing lock, but move them to a local free queue. Drop the lock and restore IRQ state before calling ieee80211_free_txskb(). WARNING: kernel/softirq.c:430 at __local_bh_enable_ip Fixes: 397a7a24ef8c ("mac80211: free ps->bc_buf skbs on vlan device stop") Assisted-by: Codex:gpt-5.5 Signed-off-by: Cen Zhang Link: https://patch.msgid.link/20260706140841.581566-1-zzzccc427@gmail.com Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin --- net/mac80211/iface.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c index eb7de2d455e1ad..3b2d51df5d9473 100644 --- a/net/mac80211/iface.c +++ b/net/mac80211/iface.c @@ -482,6 +482,7 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, bool going_do WARN_ON(!list_empty(&sdata->u.ap.vlans)); } else if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) { /* remove all packets in parent bc_buf pointing to this dev */ + __skb_queue_head_init(&freeq); ps = &sdata->bss->ps; spin_lock_irqsave(&ps->bc_buf.lock, flags); @@ -489,10 +490,15 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, bool going_do if (skb->dev == sdata->dev) { __skb_unlink(skb, &ps->bc_buf); local->total_ps_buffered--; - ieee80211_free_txskb(&local->hw, skb); + __skb_queue_tail(&freeq, skb); } } spin_unlock_irqrestore(&ps->bc_buf.lock, flags); + + skb_queue_walk_safe(&freeq, skb, tmp) { + __skb_unlink(skb, &freeq); + ieee80211_free_txskb(&local->hw, skb); + } } if (going_down) -- 2.53.0