From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 05A4F19D07E; Fri, 3 Apr 2026 08:32:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775205159; cv=none; b=OZSRK5StSnftr5vu+ntrimbF+EX9fhGV+sAQt5fwszfEr1WczBFfapovOnLmkwCh+2QhfEEyu34CrhzZQ2eliLy9vL882xoBawm8T32FQN5KNds9z0U/TgzCqw82o5CrJN9RVbf/EBFSFzCBaZGaMQ1pUzOPgyHVEuSYvQSYN2o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775205159; c=relaxed/simple; bh=X3ue6DYRmQU5xsro/VZB8UpEGt/pWXZaKTyBr9gKgGk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pV/UMNRuOiYJyhdlMdJJr5OArZWMtAkUoneENc9BXa2EMj4Lv7K68f0B82x3SDJ9eoGf0QpG3jYCb2O4ynIS+6vhjcWgGjX4pBXsPoycDXFIz/wxCRr8UC0rGlgxE86h8JoUB4GuE0syW8QnHBFghApAvCso1OdRVDbXMw56NX8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=u2hU96MR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="u2hU96MR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4A4AEC4CEF7; Fri, 3 Apr 2026 08:32:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775205158; bh=X3ue6DYRmQU5xsro/VZB8UpEGt/pWXZaKTyBr9gKgGk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=u2hU96MRIpzQYkGb167h4xmyBFNrwbLokMwgEqxXCiOPIbOq4xzTPd9wiEesX3yJo Z8QPziFbqDBpk8b77fVlER50eStl/1ltEgZgfErXp+aBW2zyuJR5evhK21HUvUsDvH NBx52eY+wyAkWj5YZtnNJnN7gachq2swi/eIuRFACHKSO3lpBvvfBwZnpr1bWX1ufZ WZmoH5cUjkQVzjhlsOVRjdSxeVXsr7H5Z7rg5MsBbtVfSH6bB9R9ZssRjblxZla8JB DgJUO6Wp+ANmkmBH9AUFeJKHNPN0JuQourHpqMluuMXyk7hiUvQC5YScTyrDR5Z9mp qfSUQTsxMrneA== Date: Fri, 3 Apr 2026 09:32:33 +0100 From: Simon Horman To: Manivannan Sadhasivam Cc: Manivannan Sadhasivam , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-arm-msm@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, andersson@kernel.org, yimingqian591@gmail.com, chris.lew@oss.qualcomm.com, stable@vger.kernel.org Subject: Re: [PATCH 2/2] net: qrtr: ns: Limit the maximum lookups per socket Message-ID: <20260403083233.GB11973@horms.kernel.org> References: <20260325104415.104972-1-manivannan.sadhasivam@oss.qualcomm.com> <20260325104415.104972-3-manivannan.sadhasivam@oss.qualcomm.com> <20260327100709.GD111839@horms.kernel.org> Precedence: bulk X-Mailing-List: stable@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: On Fri, Mar 27, 2026 at 03:47:13PM +0530, Manivannan Sadhasivam wrote: > On Fri, Mar 27, 2026 at 10:07:09AM +0000, Simon Horman wrote: > > On Wed, Mar 25, 2026 at 04:14:15PM +0530, Manivannan Sadhasivam wrote: > > > Current code does no bound checking on the number of lookups a client can > > > perform per socket. Though the code restricts the lookups to local clients, > > > there is still a possibility of a malicious local client sending a flood of > > > NEW_LOOKUP messages over the same socket. > > > > > > Fix this issue by limiting the maximum number of lookups to 64 per socket. > > > Note that, limit of 64 is chosen based on the current platform > > > requirements. If requirement changes in the future, this limit can be > > > increased. > > > > > > Cc: stable@vger.kernel.org > > > Fixes: 0c2204a4ad71 ("net: qrtr: Migrate nameservice to kernel from userspace") > > > Signed-off-by: Manivannan Sadhasivam > > > --- > > > net/qrtr/ns.c | 18 ++++++++++++++++-- > > > 1 file changed, 16 insertions(+), 2 deletions(-) > > > > > > diff --git a/net/qrtr/ns.c b/net/qrtr/ns.c > > > index fb4e8a2d370d..707fde809939 100644 > > > --- a/net/qrtr/ns.c > > > +++ b/net/qrtr/ns.c > > > @@ -70,10 +70,11 @@ struct qrtr_node { > > > u32 server_count; > > > }; > > > > > > -/* Max server limit is chosen based on the current platform requirements. If the > > > - * requirement changes in the future, this value can be increased. > > > +/* Max server, lookup limits are chosen based on the current platform requirements. > > > + * If the requirement changes in the future, these values can be increased. > > > */ > > > #define QRTR_NS_MAX_SERVERS 256 > > > +#define QRTR_NS_MAX_LOOKUPS 64 > > > > > > static struct qrtr_node *node_get(unsigned int node_id) > > > { > > > @@ -545,11 +546,24 @@ static int ctrl_cmd_new_lookup(struct sockaddr_qrtr *from, > > > struct qrtr_node *node; > > > unsigned long node_idx; > > > unsigned long srv_idx; > > > + u8 count = 0; > > > > > > /* Accept only local observers */ > > > if (from->sq_node != qrtr_ns.local_node) > > > return -EINVAL; > > > > > > + /* Make sure the client performs only maximum allowed lookups */ > > > + list_for_each_entry(lookup, &qrtr_ns.lookups, li) { > > > + if (lookup->sq.sq_node == from->sq_node && > > > + lookup->sq.sq_port == from->sq_port) > > > + count++; > > > > This feels like it could get quite expensive. > > If many lookups are added, it feels like it may be O(n^2). > > > > Lookups are not something that'll happen very often. A client only registers > for the lookup once per service that it depends on. That shouldn't be too > much. And then once lookup is registered, it will be used throughout the > lifetime of the client. > > So there is no overhead associated with this check. Thanks, and sorry for the delay: I was taking a holiday. I'm still slightly concerned that this may prove to be a problem. But we can leave that concern sit in a corner by itself for now. For this patch feel free to add, Reviewed-by: Simon Horman I notice that this series has been marked as changes requested in patchwork. So, unless it's being handled by some other means that I can't see at this moment, I think it would be best to repost this series.