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 F36843B811F; Mon, 17 Aug 2026 14:08:04 +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=1786975686; cv=none; b=uFiCWfqfSeKw8GXKL+Xo/PPClzF1MzyGpWP8V8ltTvLrSV04nBBUw3CrwOByGYNHOv4dTFAHVw03wYIFrNbondUXWBoij8mE20o2aquZ6zTMR2EOtpafjN2wOug1sv9ScvJjvmWh8AmQtuSaTrWnKrsKtAdWy1UNvEY8hzri7C0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786975686; c=relaxed/simple; bh=omEJPkNYbVzaAKnVQ7yg2ni+j7HgDN0pkooawRo0+rU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tS2FZCHUTDVJPt/u34uajAM+cIxTiLW9eocCCZLhXuYCwCWyhAspl3aZcRzlcpbIPHfQo9XJP1h1mW8oKgd2ULPIfLqcAXPJUV/J5xqensdXNGi41Aj60CTJZPYHXFXFIpWhx7TO3NLRecNUjoltcGd1p70r/jg8a01eJK57SmA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=NWmruvEh; 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="NWmruvEh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 576C31F000E9; Mon, 17 Aug 2026 14:08:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786975684; bh=gLQIykG7v+6ZZ455F3n1n9qT5ZrStdPzK5+QZdqtbR0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=NWmruvEhlvFhp8D0puvIJraC65ExLXGzbSCf7VVwX0fzAs/lgmfKfotw9yir4pLxH aLjRDn3OsFWfQT4mfyfY6vLVYIZdASB0pbLt8eba8c7OTKdGMFadajcvqXMnWd7nzv S0eeXRPjM4L3drK9hD6v+Z2gar3SvUhffQYPza2s= 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 5.10 074/389] net/packet: avoid fanout hook re-registration after unregister Date: Mon, 17 Aug 2026 15:28:33 +0200 Message-ID: <20260817132541.988463857@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132538.796021292@linuxfoundation.org> References: <20260817132538.796021292@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 5.10-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 793720e506799c..b09d1bbddde937 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -4551,7 +4551,11 @@ 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