From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from metis.whiteo.stw.pengutronix.de (metis.whiteo.stw.pengutronix.de [185.203.201.7]) (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 04CC11FA1 for ; Mon, 13 May 2024 07:14:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.203.201.7 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715584479; cv=none; b=UylFzxbvLSGB9v4q4Vg8JWbfSxNHD0Mbbra/9m6jXGe3S+1GpjMXWOVZ0hOjckJ+eXH4zUZpmGwoPjQCT+Pr6Kt8akY7dFRaMGmXWoanUsKQxSplpMdPVUS3JjpSUO18NTsMOpnkxM0o/MRzawc16rK5a/Xd2D2WuGGXsrjWPuU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715584479; c=relaxed/simple; bh=suY7gdj5WEzlYkeyc21b5k/5NgIk2dmm7ryt+mMo7mg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mQyAn6gjTUXRaXNfedf8qsxjo3D9YN65PSTnC37F67sMD1XWCEWov3L7V8Av5M8szSb+GrUacDFd6AOOghtvlxMwUUEOTJRQSG0yZViDyh2HC9H/i+Qz+EiQYoE/PLunX0ewthdnWlBtMRddWcGcCfgc2cFy/yRpMMeM+JiCuTU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de; spf=pass smtp.mailfrom=pengutronix.de; arc=none smtp.client-ip=185.203.201.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pengutronix.de Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1s6Pt9-0001Jd-LQ; Mon, 13 May 2024 09:14:23 +0200 Received: from [2a0a:edc0:2:b01:1d::c5] (helo=pty.whiteo.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1s6Pt7-0017rX-OP; Mon, 13 May 2024 09:14:21 +0200 Received: from ore by pty.whiteo.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1s6Pt7-009OQ9-24; Mon, 13 May 2024 09:14:21 +0200 Date: Mon, 13 May 2024 09:14:21 +0200 From: Oleksij Rempel To: Shigeru Yoshida Cc: robin@protonic.nl, kernel@pengutronix.de, socketcan@hartkopp.net, mkl@pengutronix.de, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-can@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+5681e40d297b30f5b513@syzkaller.appspotmail.com Subject: Re: [PATCH] can: j1939: Initialize unused data in j1939_send_one() Message-ID: References: <20240512160307.2604215-1-syoshida@redhat.com> Precedence: bulk X-Mailing-List: linux-can@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240512160307.2604215-1-syoshida@redhat.com> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: ore@pengutronix.de X-SA-Exim-Scanned: No (on metis.whiteo.stw.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-can@vger.kernel.org Hi, On Mon, May 13, 2024 at 01:03:07AM +0900, Shigeru Yoshida wrote: > syzbot reported kernel-infoleak in raw_recvmsg() [1]. j1939_send_one() > creates full frame including unused data, but it doesn't initialize it. > This causes the kernel-infoleak issue. Fix this by initializing unused > data. > > [1] > BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline] > BUG: KMSAN: kernel-infoleak in copy_to_user_iter lib/iov_iter.c:24 [inline] > BUG: KMSAN: kernel-infoleak in iterate_ubuf include/linux/iov_iter.h:29 [inline] > BUG: KMSAN: kernel-infoleak in iterate_and_advance2 include/linux/iov_iter.h:245 [inline] > BUG: KMSAN: kernel-infoleak in iterate_and_advance include/linux/iov_iter.h:271 [inline] > BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185 > instrument_copy_to_user include/linux/instrumented.h:114 [inline] > copy_to_user_iter lib/iov_iter.c:24 [inline] > iterate_ubuf include/linux/iov_iter.h:29 [inline] > iterate_and_advance2 include/linux/iov_iter.h:245 [inline] > iterate_and_advance include/linux/iov_iter.h:271 [inline] > _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185 > copy_to_iter include/linux/uio.h:196 [inline] > memcpy_to_msg include/linux/skbuff.h:4113 [inline] > raw_recvmsg+0x2b8/0x9e0 net/can/raw.c:1008 > sock_recvmsg_nosec net/socket.c:1046 [inline] > sock_recvmsg+0x2c4/0x340 net/socket.c:1068 > ____sys_recvmsg+0x18a/0x620 net/socket.c:2803 > ___sys_recvmsg+0x223/0x840 net/socket.c:2845 > do_recvmmsg+0x4fc/0xfd0 net/socket.c:2939 > __sys_recvmmsg net/socket.c:3018 [inline] > __do_sys_recvmmsg net/socket.c:3041 [inline] > __se_sys_recvmmsg net/socket.c:3034 [inline] > __x64_sys_recvmmsg+0x397/0x490 net/socket.c:3034 > x64_sys_call+0xf6c/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:300 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Uninit was created at: > slab_post_alloc_hook mm/slub.c:3804 [inline] > slab_alloc_node mm/slub.c:3845 [inline] > kmem_cache_alloc_node+0x613/0xc50 mm/slub.c:3888 > kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:577 > __alloc_skb+0x35b/0x7a0 net/core/skbuff.c:668 > alloc_skb include/linux/skbuff.h:1313 [inline] > alloc_skb_with_frags+0xc8/0xbf0 net/core/skbuff.c:6504 > sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2795 > sock_alloc_send_skb include/net/sock.h:1842 [inline] > j1939_sk_alloc_skb net/can/j1939/socket.c:878 [inline] > j1939_sk_send_loop net/can/j1939/socket.c:1142 [inline] > j1939_sk_sendmsg+0xc0a/0x2730 net/can/j1939/socket.c:1277 > sock_sendmsg_nosec net/socket.c:730 [inline] > __sock_sendmsg+0x30f/0x380 net/socket.c:745 > ____sys_sendmsg+0x877/0xb60 net/socket.c:2584 > ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 > __sys_sendmsg net/socket.c:2667 [inline] > __do_sys_sendmsg net/socket.c:2676 [inline] > __se_sys_sendmsg net/socket.c:2674 [inline] > __x64_sys_sendmsg+0x307/0x4a0 net/socket.c:2674 > x64_sys_call+0xc4b/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:47 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Bytes 12-15 of 16 are uninitialized > Memory access of size 16 starts at ffff888120969690 > Data copied to user address 00000000200017c0 > > CPU: 1 PID: 5050 Comm: syz-executor198 Not tainted 6.9.0-rc5-syzkaller-00031-g71b1543c83d6 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 > > Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol") > Reported-and-tested-by: syzbot+5681e40d297b30f5b513@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=5681e40d297b30f5b513 > Signed-off-by: Shigeru Yoshida Thank you for your investigation! > --- > net/can/j1939/main.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c > index a6fb89fa6278..df01628c6509 100644 > --- a/net/can/j1939/main.c > +++ b/net/can/j1939/main.c > @@ -344,6 +344,9 @@ int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb) > /* make it a full can frame again */ > skb_put(skb, J1939_CAN_FTR + (8 - dlc)); > > + /* initialize unused data */ > + memset(cf->data + dlc, 0, 8 - dlc); > + > canid = CAN_EFF_FLAG | > (skcb->priority << 26) | > (skcb->addr.pgn << 8) | > -- > 2.44.0 Can you please change it to: --- a/net/can/j1939/main.c +++ b/net/can/j1939/main.c @@ -30,10 +30,6 @@ MODULE_ALIAS("can-proto-" __stringify(CAN_J1939)); /* CAN_HDR: #bytes before can_frame data part */ #define J1939_CAN_HDR (offsetof(struct can_frame, data)) -/* CAN_FTR: #bytes beyond data part */ -#define J1939_CAN_FTR (sizeof(struct can_frame) - J1939_CAN_HDR - \ - sizeof(((struct can_frame *)0)->data)) - /* lowest layer */ static void j1939_can_recv(struct sk_buff *iskb, void *data) { @@ -342,7 +338,7 @@ int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb) memset(cf, 0, J1939_CAN_HDR); /* make it a full can frame again */ - skb_put(skb, J1939_CAN_FTR + (8 - dlc)); + skb_put_zero(skb, 8 - dlc); canid = CAN_EFF_FLAG | (skcb->priority << 26) | With this change included, you can add my: Acked-by: Oleksij Rempel Regards, Oleksij -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |