From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2169C208C7 for ; Tue, 31 Oct 2023 17:48:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="EoGPup/U" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90876C433CC; Tue, 31 Oct 2023 17:48:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1698774507; bh=xrROycKAnd/qnrxWLF0cMljlGK1iYmbbv1hB7B33zvY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EoGPup/UL2qoT7S5EhoeLPXLMWRcV5uzscJC2JNvcWuArI8xZHaXJa5Eo6OjG+l7y yf8krrNv4h/kAevN+oC0gkNJze6h0ysVj0US8aVJVyFYKMV92qaFOdveQXmuESsVJ9 Dq6fIxqielmBnlDmrZ0zbpUGsnW0HY6+bGXSR6Zc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Moritz=20Wanzenb=C3=B6ck?= , Chuck Lever , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.5 070/112] net/handshake: fix file ref count in handshake_nl_accept_doit() Date: Tue, 31 Oct 2023 18:01:11 +0100 Message-ID: <20231031165903.522946684@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231031165901.318222981@linuxfoundation.org> References: <20231031165901.318222981@linuxfoundation.org> User-Agent: quilt/0.67 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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Moritz Wanzenböck [ Upstream commit 7798b59409c345d4a6034a4326bceb9f7e2e8b58 ] If req->hr_proto->hp_accept() fail, we call fput() twice: Once in the error path, but also a second time because sock->file is at that point already associated with the file descriptor. Once the task exits, as it would probably do after receiving an error reading from netlink, the fd is closed, calling fput() a second time. To fix, we move installing the file after the error path for the hp_accept() call. In the case of errors we simply put the unused fd. In case of success we can use fd_install() to link the sock->file to the reserved fd. Fixes: 7ea9c1ec66bc ("net/handshake: Fix handshake_dup() ref counting") Signed-off-by: Moritz Wanzenböck Reviewed-by: Chuck Lever Link: https://lore.kernel.org/r/20231019125847.276443-1-moritz.wanzenboeck@linbit.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/handshake/netlink.c | 30 +++++------------------------- 1 file changed, 5 insertions(+), 25 deletions(-) diff --git a/net/handshake/netlink.c b/net/handshake/netlink.c index d0bc1dd8e65a8..80c7302692c74 100644 --- a/net/handshake/netlink.c +++ b/net/handshake/netlink.c @@ -87,29 +87,6 @@ struct nlmsghdr *handshake_genl_put(struct sk_buff *msg, } EXPORT_SYMBOL(handshake_genl_put); -/* - * dup() a kernel socket for use as a user space file descriptor - * in the current process. The kernel socket must have an - * instatiated struct file. - * - * Implicit argument: "current()" - */ -static int handshake_dup(struct socket *sock) -{ - struct file *file; - int newfd; - - file = get_file(sock->file); - newfd = get_unused_fd_flags(O_CLOEXEC); - if (newfd < 0) { - fput(file); - return newfd; - } - - fd_install(newfd, file); - return newfd; -} - int handshake_nl_accept_doit(struct sk_buff *skb, struct genl_info *info) { struct net *net = sock_net(skb->sk); @@ -133,17 +110,20 @@ int handshake_nl_accept_doit(struct sk_buff *skb, struct genl_info *info) goto out_status; sock = req->hr_sk->sk_socket; - fd = handshake_dup(sock); + fd = get_unused_fd_flags(O_CLOEXEC); if (fd < 0) { err = fd; goto out_complete; } + err = req->hr_proto->hp_accept(req, info, fd); if (err) { - fput(sock->file); + put_unused_fd(fd); goto out_complete; } + fd_install(fd, get_file(sock->file)); + trace_handshake_cmd_accept(net, req, req->hr_sk, fd); return 0; -- 2.42.0