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 D8BFC194A6C; Thu, 30 Jul 2026 15:35:37 +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=1785425738; cv=none; b=qb0HnUpyk7mTc6mwsScXOaXwdYcyJR0qFWIs0ejlSFm094ATWlvMXs+uAq0ZwG2F+Y6ZKQdXj1E3bNRPuuUrljWaiu/UaBUSOqS7lmKvDCfw74Sfjkdqp6lXWnMHxQv82X1oyMtovsYngl/D/JdH6TnlbzHE4MeDxlHS1MtPN6w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785425738; c=relaxed/simple; bh=IBy8KkoZkzv6pKsk+vHkFmHyw5Wnbo3O1n1jupamTLY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FCGeOjrj7LtaNzC9JZz4w7ADGr7dCaQ7HzEL6u0ry9sodTeb95fZ24lAMvWjVEreA+4FTyhvakTaqaDqS4wE7wXnsbxgPGsIri3UrVDXmctA39HjTAq94cBC8TEMMf97SUtaD3VKmfdkMMZ1JDMQxMTc/KshajA7YiMQ0e42T9k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xGRrWPoW; 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="xGRrWPoW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 412681F000E9; Thu, 30 Jul 2026 15:35:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785425737; bh=+Ww4ZJq1C8F9QhezUsPbGdqPlxFrpqDy5R+SpIDguqY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=xGRrWPoWJnvGIZUbjgIiu+GSH3qzHfzm2vwG7p76okXb4vzDz2f6OZX+HZHgHm26A LcrfVbkzhNtS3nrLoL+KLiA/0wENd0IWwpaPP14kuSggzVGnVB9G1kLnjvUbHv4Dj6 L3ZzrgJS+Io+JdIAa+IQfQEqjSBlRmmuTJQ/gOR4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Lee , Willem de Bruijn , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 173/602] net/packet: avoid fanout hook re-registration after unregister Date: Thu, 30 Jul 2026 16:09:25 +0200 Message-ID: <20260730141439.605047379@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141435.976815864@linuxfoundation.org> References: <20260730141435.976815864@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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Lee [ Upstream commit 50aff80475abd3533eef4320477037e6fcc6b56e ] packet_set_ring() temporarily detaches a socket from packet delivery while reconfiguring its ring. It records the previous running state, clears po->num, unregisters the protocol hook when needed, drops po->bind_lock, and later restores po->num and re-registers the hook from the saved was_running value. That unlocked window can race with NETDEV_UNREGISTER. The notifier can observe the socket as not running, skip __unregister_prot_hook(), and invalidate the per-socket binding by setting po->ifindex to -1 and clearing po->prot_hook.dev. A one-member fanout group can still retain its shared fanout hook device pointer. When packet_set_ring() resumes, re-registering solely from the stale was_running state can re-add the fanout hook after the device has been unregistered. Treat po->ifindex == -1 as an invalidated binding after reacquiring po->bind_lock. This is distinct from ifindex 0, the normal unbound/wildcard state: ifindex -1 marks an existing device binding that was invalidated when the device was unregistered. Restore po->num as before, but do not re-register the hook if device unregister already detached the socket. Fixes: dc99f600698d ("packet: Add fanout support.") Link: https://lore.kernel.org/netdev/20260701113947.23180-1-david.lee@trailofbits.com/ Signed-off-by: David Lee Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20260707104440.833129-1-david.lee@trailofbits.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/packet/af_packet.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 562c860cca577a..c5900752522652 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -4604,7 +4604,11 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, spin_lock(&po->bind_lock); WRITE_ONCE(po->num, num); - if (was_running) + /* + * NETDEV_UNREGISTER may have invalidated the binding while bind_lock + * was dropped above. Do not re-add a fanout hook to a dead device. + */ + if (was_running && READ_ONCE(po->ifindex) != -1) register_prot_hook(sk); spin_unlock(&po->bind_lock); -- 2.53.0