From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B70C0C43381 for ; Thu, 21 Feb 2019 22:14:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 877AF2083B for ; Thu, 21 Feb 2019 22:14:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550787289; bh=GDzXP+vewXnT/BOaTfeEpZjSyVo4KGn6DfNms2wc0+A=; h=From:To:Cc:Subject:Date:List-ID:From; b=tblBBfeNCAI5n2Z1StrI0rz9g/0+JLJv/Wnj6m0Nyj4sx95SI4Z+TX4VuMPe3yWSf vd8musCMgMqOyx6XP59M0Zbn9dbFIRcx8jCEaRlFOdbgAm2vcUuPlsajmtujSVWvxg 2r4njMHgVqJMDy1KA55BueJW53jAYMKllG/nCGGo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726998AbfBUWOo (ORCPT ); Thu, 21 Feb 2019 17:14:44 -0500 Received: from mail.kernel.org ([198.145.29.99]:46132 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726075AbfBUWOo (ORCPT ); Thu, 21 Feb 2019 17:14:44 -0500 Received: from ebiggers-linuxstation.mtv.corp.google.com (unknown [104.132.1.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5034C20818; Thu, 21 Feb 2019 22:14:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550787283; bh=GDzXP+vewXnT/BOaTfeEpZjSyVo4KGn6DfNms2wc0+A=; h=From:To:Cc:Subject:Date:From; b=m1rkYksyangNn476aVbGORvImpfvrRpcLoM4WbhbjBE38KoqNn2ZHxw8Nu0HbfoC9 1X5+KdtE3hz/nAY8oz5wV2wkG7qUjrvn97NzAesqw8furxkdgXHrm6+94v6B9iWhUg WnsZWvTCFKe0f0iZWfwqKYYGXWBZHoJnvLPjpbuw= From: Eric Biggers To: netdev@vger.kernel.org, "David S . Miller" Cc: linux-kernel@vger.kernel.org, Mao Wenan , Cong Wang , Lorenzo Colitti , Tetsuo Handa , Al Viro , Eric Biggers Subject: [PATCH net] net: socket: set sock->sk to NULL after calling proto_ops::release() Date: Thu, 21 Feb 2019 14:13:56 -0800 Message-Id: <20190221221356.173485-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.21.0.rc0.258.g878e2cd30e-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Eric Biggers Commit 9060cb719e61 ("net: crypto set sk to NULL when af_alg_release.") fixed a use-after-free in sockfs_setattr() when an AF_ALG socket is closed concurrently with fchownat(). However, it ignored that many other proto_ops::release() methods don't set sock->sk to NULL and therefore allow the same use-after-free: - base_sock_release - bnep_sock_release - cmtp_sock_release - data_sock_release - dn_release - hci_sock_release - hidp_sock_release - iucv_sock_release - l2cap_sock_release - llcp_sock_release - llc_ui_release - rawsock_release - rfcomm_sock_release - sco_sock_release - svc_release - vcc_release - x25_release Rather than fixing all these and relying on every socket type to get this right forever, just make __sock_release() set sock->sk to NULL itself after calling proto_ops::release(). Reproducer that produces the KASAN splat when any of these socket types are configured into the kernel: #include #include #include #include pthread_t t; volatile int fd; void *close_thread(void *arg) { for (;;) { usleep(rand() % 100); close(fd); } } int main() { pthread_create(&t, NULL, close_thread, NULL); for (;;) { fd = socket(rand() % 50, rand() % 11, 0); fchownat(fd, "", 1000, 1000, 0x1000); close(fd); } } Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.") Cc: # v4.10+ Signed-off-by: Eric Biggers --- NOTE: I am not an expert in the networking code, so please carefully check that I haven't missed some reason why this simple fix won't do. net/socket.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/socket.c b/net/socket.c index d80d87a395ea..320f51b22b19 100644 --- a/net/socket.c +++ b/net/socket.c @@ -577,6 +577,7 @@ static void __sock_release(struct socket *sock, struct inode *inode) if (inode) inode_lock(inode); sock->ops->release(sock); + sock->sk = NULL; if (inode) inode_unlock(inode); sock->ops = NULL; -- 2.21.0.rc0.258.g878e2cd30e-goog