From patchwork Fri Aug 14 11:04:23 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Kleine-Budde X-Patchwork-Id: 262561 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=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 46E78C433E4 for ; Fri, 14 Aug 2020 11:04:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2E764206DA for ; Fri, 14 Aug 2020 11:04:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727896AbgHNLEe (ORCPT ); Fri, 14 Aug 2020 07:04:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727886AbgHNLEd (ORCPT ); Fri, 14 Aug 2020 07:04:33 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E8039C061385 for ; Fri, 14 Aug 2020 04:04:32 -0700 (PDT) Received: from heimdall.vpn.pengutronix.de ([2001:67c:670:205:1d::14] helo=blackshift.org) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1k6XVe-00040D-Rp; Fri, 14 Aug 2020 13:04:30 +0200 From: Marc Kleine-Budde To: netdev@vger.kernel.org Cc: davem@davemloft.net, linux-can@vger.kernel.org, kernel@pengutronix.de, Eric Dumazet , syzbot , Robin van der Gracht , Oleksij Rempel , Marc Kleine-Budde Subject: [PATCH 1/6] can: j1939: fix kernel-infoleak in j1939_sk_sock2sockaddr_can() Date: Fri, 14 Aug 2020 13:04:23 +0200 Message-Id: <20200814110428.405051-2-mkl@pengutronix.de> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200814110428.405051-1-mkl@pengutronix.de> References: <20200814110428.405051-1-mkl@pengutronix.de> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:205:1d::14 X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: netdev@vger.kernel.org Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Eric Dumazet syzbot found that at least 2 bytes of kernel information were leaked during getsockname() on AF_CAN CAN_J1939 socket. Since struct sockaddr_can has in fact two holes, simply clear the whole area before filling it with useful data. BUG: KMSAN: kernel-infoleak in kmsan_copy_to_user+0x81/0x90 mm/kmsan/kmsan_hooks.c:253 CPU: 0 PID: 8466 Comm: syz-executor511 Not tainted 5.8.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x21c/0x280 lib/dump_stack.c:118 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121 kmsan_internal_check_memory+0x238/0x3d0 mm/kmsan/kmsan.c:423 kmsan_copy_to_user+0x81/0x90 mm/kmsan/kmsan_hooks.c:253 instrument_copy_to_user include/linux/instrumented.h:91 [inline] _copy_to_user+0x18e/0x260 lib/usercopy.c:39 copy_to_user include/linux/uaccess.h:186 [inline] move_addr_to_user+0x3de/0x670 net/socket.c:237 __sys_getsockname+0x407/0x5e0 net/socket.c:1909 __do_sys_getsockname net/socket.c:1920 [inline] __se_sys_getsockname+0x91/0xb0 net/socket.c:1917 __x64_sys_getsockname+0x4a/0x70 net/socket.c:1917 do_syscall_64+0xad/0x160 arch/x86/entry/common.c:386 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x440219 Code: Bad RIP value. RSP: 002b:00007ffe5ee150c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000033 RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440219 RDX: 0000000020000240 RSI: 0000000020000100 RDI: 0000000000000003 RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401a20 R13: 0000000000401ab0 R14: 0000000000000000 R15: 0000000000000000 Local variable ----address@__sys_getsockname created at: __sys_getsockname+0x91/0x5e0 net/socket.c:1894 __sys_getsockname+0x91/0x5e0 net/socket.c:1894 Bytes 2-3 of 24 are uninitialized Memory access of size 24 starts at ffff8880ba2c7de8 Data copied to user address 0000000020000100 Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol") Signed-off-by: Eric Dumazet Reported-by: syzbot Cc: Robin van der Gracht Cc: Oleksij Rempel Cc: Pengutronix Kernel Team Cc: linux-can@vger.kernel.org Acked-by: Oleksij Rempel Link: https://lore.kernel.org/r/20200813161834.4021638-1-edumazet@google.com Signed-off-by: Marc Kleine-Budde --- net/can/j1939/socket.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c index 78ff9b3f1d40..b634b680177f 100644 --- a/net/can/j1939/socket.c +++ b/net/can/j1939/socket.c @@ -553,6 +553,11 @@ static int j1939_sk_connect(struct socket *sock, struct sockaddr *uaddr, static void j1939_sk_sock2sockaddr_can(struct sockaddr_can *addr, const struct j1939_sock *jsk, int peer) { + /* There are two holes (2 bytes and 3 bytes) to clear to avoid + * leaking kernel information to user space. + */ + memset(addr, 0, J1939_MIN_NAMELEN); + addr->can_family = AF_CAN; addr->can_ifindex = jsk->ifindex; addr->can_addr.j1939.pgn = jsk->addr.pgn;