From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZp1qTQuE3g1cp6kKzjdWdQfcG5yo5VeThsEtZYT1RXjI/jUnysEALJlbDMWPaDWicjZUmyp ARC-Seal: i=1; a=rsa-sha256; t=1524837720; cv=none; d=google.com; s=arc-20160816; b=g328yo7ncRqKqDyfo13H9ixprrIgHcDC0vjzT7iP4Q1kuN4iVTeVm+xprk1oN+3rNo YMPQjXxd31w1qGJEbKgXFNMsc3jzmhKKpfT4YNXt/AO0DP9/anAY6RbxK/ubMihZfV4l 5BZM8MeoyMKVilcAeF+SbbUyXOwgNHWyhZ3+nCk+Crrbgizh5w8+d99h3Jh7dSOBVRKj mMZ3IALpZWOLVnkvqEbU3S6xTB5KvoZpCIKrvoO8x6YFvrMxVzjpyuWjRbQzjcospkoc 04VpGw8po8SjMXtZqD1BEK9xBjR8JQD16tWCuQKqS6CUE+bSNsgSJV7WuDsDWKVWpyJU Ty3g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:dmarc-filter:arc-authentication-results; bh=tQNuKenMlLKWt0o+r8JiuDLiwipnbBYvK6v1F1n7Sjk=; b=JyRSOw6ZigMRcJIcHMXNdFx+Qln6ExO5CR6KHVdWj2fN659NSQ8DbrfP1BRwVxVpN/ SvlChH+EY7qj7wAZKkh+uethsOioJV0534lNhEKKuhJj2XbIHtXg13fLx9n1RnMD/9+m 23796VJCtBoEQmN4o73+zNwIUgGe4qN7rAA820/XYJhdtwZXzg0K21QnSfadFB9l8N8S x+Qk/fsnwsSxTCKcIf8dNLp3ZFsVUWwQRNchwfkRbdpInFftFP20jnbnex/CU2USkof2 6rhnH7vtoja20acZgzJPUciGLxtNI5T91i99URrx9ElqWT6ishUO8K81pQ+51jT3h5RE 2hgg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of srs0=4/0d=hq=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=4/0d=HQ=linuxfoundation.org=gregkh@kernel.org Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of srs0=4/0d=hq=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=4/0d=HQ=linuxfoundation.org=gregkh@kernel.org DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1C84E21897 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=fail smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+6e181fc95081c2cf9051@syzkaller.appspotmail.com, Cong Wang , "David S. Miller" Subject: [PATCH 4.4 40/50] llc: hold llc_sap before release_sock() Date: Fri, 27 Apr 2018 15:58:42 +0200 Message-Id: <20180427135658.043224496@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180427135655.623669681@linuxfoundation.org> References: <20180427135655.623669681@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1598908022431860439?= X-GMAIL-MSGID: =?utf-8?q?1598908238092414096?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cong Wang [ Upstream commit f7e43672683b097bb074a8fe7af9bc600a23f231 ] syzbot reported we still access llc->sap in llc_backlog_rcv() after it is freed in llc_sap_remove_socket(): Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430 llc_conn_ac_send_sabme_cmd_p_set_x+0x3a8/0x460 net/llc/llc_c_ac.c:785 llc_exec_conn_trans_actions net/llc/llc_conn.c:475 [inline] llc_conn_service net/llc/llc_conn.c:400 [inline] llc_conn_state_process+0x4e1/0x13a0 net/llc/llc_conn.c:75 llc_backlog_rcv+0x195/0x1e0 net/llc/llc_conn.c:891 sk_backlog_rcv include/net/sock.h:909 [inline] __release_sock+0x12f/0x3a0 net/core/sock.c:2335 release_sock+0xa4/0x2b0 net/core/sock.c:2850 llc_ui_release+0xc8/0x220 net/llc/af_llc.c:204 llc->sap is refcount'ed and llc_sap_remove_socket() is paired with llc_sap_add_socket(). This can be amended by holding its refcount before llc_sap_remove_socket() and releasing it after release_sock(). Reported-by: Signed-off-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/llc/af_llc.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/net/llc/af_llc.c +++ b/net/llc/af_llc.c @@ -187,6 +187,7 @@ static int llc_ui_release(struct socket { struct sock *sk = sock->sk; struct llc_sock *llc; + struct llc_sap *sap; if (unlikely(sk == NULL)) goto out; @@ -197,9 +198,15 @@ static int llc_ui_release(struct socket llc->laddr.lsap, llc->daddr.lsap); if (!llc_send_disc(sk)) llc_ui_wait_for_disc(sk, sk->sk_rcvtimeo); + sap = llc->sap; + /* Hold this for release_sock(), so that llc_backlog_rcv() could still + * use it. + */ + llc_sap_hold(sap); if (!sock_flag(sk, SOCK_ZAPPED)) llc_sap_remove_socket(llc->sap, sk); release_sock(sk); + llc_sap_put(sap); if (llc->dev) dev_put(llc->dev); sock_put(sk);