From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from vmicros1.altlinux.org (vmicros1.altlinux.org [194.107.17.57]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CDBBB1A2C25; Fri, 12 Dec 2025 01:01:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=194.107.17.57 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765501307; cv=none; b=jiMUylk31fxD3elgF60pnnuTexQre1EpUqR9VR2Y/p+Vw6xZgbvBShLwffr4RzDsaPDUPFQAz12wey9AiO0IORQYEUIC8/bk2IKHY16zZk4n4a+L1dGZr2wZv57xgQe85aJfAI2PRyL6d+O41SeNPzz8EJuKnWSDqbFuVWHOwNI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765501307; c=relaxed/simple; bh=RvqkoCui2IQB/RgbUMRXZgPo927HN07kQXHCLZ0t/ko=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=djL5bI0J0wYTjKOsKWxqq28IHCt8De6u7G1JDy3jH8XJFBE9t8cci9fIREy3Bt6fC0sfnzBVMlTEGz3zvhccTDG6FM4hyViIryrmXCGK+mH4asK/h6demHe7fje/gxNvvmeEefLYSWvwakY31C4h1wmRl/vC0OeIf5JircLumGw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=altlinux.org; spf=pass smtp.mailfrom=altlinux.org; arc=none smtp.client-ip=194.107.17.57 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=altlinux.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=altlinux.org Received: from imap.altlinux.org (imap.altlinux.org [194.107.17.38]) by vmicros1.altlinux.org (Postfix) with ESMTP id D440E72C8CC; Fri, 12 Dec 2025 03:54:26 +0300 (MSK) Received: from pony.office.basealt.ru (unknown [193.43.10.9]) by imap.altlinux.org (Postfix) with ESMTPSA id CCDD536D016E; Fri, 12 Dec 2025 03:54:26 +0300 (MSK) Received: by pony.office.basealt.ru (Postfix, from userid 500) id AD8A7360D63C; Fri, 12 Dec 2025 03:54:26 +0300 (MSK) Date: Fri, 12 Dec 2025 03:54:26 +0300 From: Vitaly Chikunov To: Ranganath V N , linux-rt-devel@lists.linux.dev Cc: edumazet@google.com, davem@davemloft.net, david.hunter.linux@gmail.com, horms@kernel.org, jhs@mojatatu.com, jiri@resnulli.us, khalid@kernel.org, kuba@kernel.org, pabeni@redhat.com, xiyou.wangcong@gmail.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, skhan@linuxfoundation.org Subject: Re: [PATCH net v4 2/2] net: sched: act_ife: initialize struct tc_ife to fix KMSAN kernel-infoleak Message-ID: References: <20251109091336.9277-1-vnranganath.20@gmail.com> <20251109091336.9277-3-vnranganath.20@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251109091336.9277-3-vnranganath.20@gmail.com> On Sun, Nov 09, 2025 at 02:43:36PM +0530, Ranganath V N wrote: > Fix a KMSAN kernel-infoleak detected by the syzbot . > > [net?] KMSAN: kernel-infoleak in __skb_datagram_iter > > In tcf_ife_dump(), the variable 'opt' was partially initialized using a > designatied initializer. While the padding bytes are reamined > uninitialized. nla_put() copies the entire structure into a > netlink message, these uninitialized bytes leaked to userspace. > > Initialize the structure with memset before assigning its fields > to ensure all members and padding are cleared prior to beign copied. > > This change silences the KMSAN report and prevents potential information > leaks from the kernel memory. > > This fix has been tested and validated by syzbot. This patch closes the > bug reported at the following syzkaller link and ensures no infoleak. > > Reported-by: syzbot+0c85cae3350b7d486aee@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=0c85cae3350b7d486aee > Tested-by: syzbot+0c85cae3350b7d486aee@syzkaller.appspotmail.com > Fixes: ef6980b6becb ("introduce IFE action") > Signed-off-by: Ranganath V N > --- > net/sched/act_ife.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c > index 107c6d83dc5c..7c6975632fc2 100644 > --- a/net/sched/act_ife.c > +++ b/net/sched/act_ife.c > @@ -644,13 +644,15 @@ static int tcf_ife_dump(struct sk_buff *skb, struct tc_action *a, int bind, > unsigned char *b = skb_tail_pointer(skb); > struct tcf_ife_info *ife = to_ife(a); > struct tcf_ife_params *p; > - struct tc_ife opt = { > - .index = ife->tcf_index, > - .refcnt = refcount_read(&ife->tcf_refcnt) - ref, > - .bindcnt = atomic_read(&ife->tcf_bindcnt) - bind, > - }; > + struct tc_ife opt; > struct tcf_t t; > > + memset(&opt, 0, sizeof(opt)); > + > + opt.index = ife->tcf_index, > + opt.refcnt = refcount_read(&ife->tcf_refcnt) - ref, > + opt.bindcnt = atomic_read(&ife->tcf_bindcnt) - bind, Are you sure this is correct to delimit with commas instead of semicolons? This already causes build failures of 5.10.247-rt141 kernel, because their spin_lock_bh unrolls into do { .. } while (0): CC [M] net/sched/act_ife.o In file included from ./include/linux/spinlock.h:329, from ./include/linux/mmzone.h:8, from ./include/linux/gfp.h:6, from ./include/linux/mm.h:10, from ./include/linux/bvec.h:14, from ./include/linux/skbuff.h:17, from net/sched/act_ife.c:20: net/sched/act_ife.c: In function 'tcf_ife_dump': ./include/linux/spinlock_rt.h:44:2: error: expected expression before 'do' 44 | do { \ | ^~ net/sched/act_ife.c:655:2: note: in expansion of macro 'spin_lock_bh' 655 | spin_lock_bh(&ife->tcf_lock); | ^~~~~~~~~~~~ make[2]: *** [scripts/Makefile.build:286: net/sched/act_ife.o] Error 1 make[2]: *** Waiting for unfinished jobs.... Thanks, > + > spin_lock_bh(&ife->tcf_lock); > opt.action = ife->tcf_action; > p = rcu_dereference_protected(ife->params, > -- > 2.43.0 >