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 B0861248F47; Sun, 14 Dec 2025 21:38:24 +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=1765748308; cv=none; b=N6U4CLAjXgcGSpCwGcz4wndsx+g4/hhezI2PdG03n8PpSgsVx3X2I+ek+2D9khXb++wnJPZKMBlR/Xu3r/OIvNElnMda94/bXVx/AApSppgip/mGm/KKKdm+2BSsABx1HZii+rqN3YOZ2ovClD/A7f+au+/Jej0MmgwxHx8oxK4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765748308; c=relaxed/simple; bh=NYLyzvVuuleE9gG/8P+CRXYvr4qbLrmQTlA3ApljXEk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Zyn7u0XFsY2YY7Vq4Aqti+LZFiPLZnYaClsbknOJPpzd+p60faWJY5RYirTG+8F9GW9Vd9LpBr8R0eaW04wLimTWMjT24KIJUgAegRucjp/W3bfSoncXJDhNuh6QbG8+001uISFBte4OciWQLJg0xwQy7ERoTy3vaZ7w322jASk= 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 E892572C8CC; Mon, 15 Dec 2025 00:38:16 +0300 (MSK) Received: from altlinux.org (unknown [193.43.10.9]) by imap.altlinux.org (Postfix) with ESMTPSA id D194B36D00D3; Mon, 15 Dec 2025 00:38:16 +0300 (MSK) Date: Mon, 15 Dec 2025 00:38:16 +0300 From: Vitaly Chikunov To: Jamal Hadi Salim , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt Cc: Ranganath V N , linux-rt-devel@lists.linux.dev, edumazet@google.com, davem@davemloft.net, david.hunter.linux@gmail.com, horms@kernel.org, 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: <3kwhg36anlckq57bez25aimvyj@altlinux.org> 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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Jamal, and linux-rt-devel, On Fri, Dec 12, 2025 at 11:29:24AM -0500, Jamal Hadi Salim wrote: > On Fri, Dec 12, 2025 at 11:26 AM Jamal Hadi Salim wrote: > > > > On Thu, Dec 11, 2025 at 7:54 PM Vitaly Chikunov wrote: > > > > > > 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): > > > > > > > Do you have access to this? > > commit 205305c028ad986d0649b8b100bab6032dcd1bb5 > > Author: Chen Ni > > Date: Wed Nov 12 15:27:09 2025 +0800 > > > > net/sched: act_ife: convert comma to semicolon > > > > Sigh. I see the problem: that patch did not have a Fixes tag; > otherwise, it would have been backported. Thanks! I will pick this for the local builds. But, perhaps, someone should send it to stable@kernel.org to fix the older -rt kernels too. Thanks, > > cheers, > jamal