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 60FCF4EB45 for ; Tue, 27 Feb 2024 17:39:28 +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=1709055568; cv=none; b=AkkDJul0ZXDqvxs0HQBI/w3OCOEkArEdE24R5Z8wPkUp9bYvmshbV2+5sTS1quBvXZRd09X0zhTxxVRfeybSPG0S0sGOt5GGySLquQqQo+HagI21wyfyl5XYSwDm05uuwXHnpvaJv6SfXBSTRFovYsXvkH7IjnoTW07xdrBo+G8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709055568; c=relaxed/simple; bh=4lIrLbA2e0AWKuLo9IgLJsmE+6Bg8bKIJsvGgGTTZVo=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=CLQHCQ0KqZRt1JKfVxyu0+kGqaky0YcMr0uH+PdWBM6Gak2mXK7HYCY4+BytR3ATibXmnSF6d9uB0xefNzrs44ZUHisDUGg76WLuTCBY1m42wqUdJoZhrXoqPNuEwolQ2os/Zrwz+hON81zOS3cueQYjs76TI/L+juNz/S9PQwg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dkhd1iZN; 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="dkhd1iZN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DFAB0C433F1; Tue, 27 Feb 2024 17:39:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1709055568; bh=4lIrLbA2e0AWKuLo9IgLJsmE+6Bg8bKIJsvGgGTTZVo=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=dkhd1iZNaYO+Va0TqWdrMFKDkkD/XQKkf3vLF3hKY+58SpzRuSQPLHnB3xBzb+BIB se64ON50z6sgRsX3XH2QlQdb9FqrGTZWfGRYatnYOd6aJ3i6nDzWL4zq2HC0q7Fw7Q OKG8hBVE3E6YJIFUhWUAfwSour3hIh+da21ysg2yYMhMFx9IhhBTlMK2+JwASbIQ3g nRohXQ/jihsgMXhUPDTiYrClSQ0lI8rWZ+6zuZUHJZfKcfKCqbzqTXnoBcJSOdCki2 PaUg5C10MIkxn5kch3PpwhGM8eZD4aay+JmZK2DEuiIx8iIsNvIrpzw0W3NpL3W/to HAbh659zfRpRQ== Date: Tue, 27 Feb 2024 11:39:26 -0600 From: Bjorn Helgaas To: Greg Kroah-Hartman Cc: Carlos =?utf-8?B?TMOzcGV6?= , cve@kernel.org, linux-kernel@vger.kernel.org, Bjorn Helgaas , Jonas Gorski , Andy Shevchenko , Mika Westerberg Subject: Re: CVE-2023-52466: PCI: Avoid potential out-of-bounds read in pci_dev_for_each_resource() Message-ID: <20240227173926.GA242161@bhelgaas> Precedence: bulk X-Mailing-List: linux-kernel@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: <2024022706-kindle-tapering-5f66@gregkh> On Tue, Feb 27, 2024 at 06:24:38PM +0100, Greg Kroah-Hartman wrote: > On Tue, Feb 27, 2024 at 09:07:44AM -0600, Bjorn Helgaas wrote: > > [+cc Mika, author of 09cc90063240] > > > > On Tue, Feb 27, 2024 at 02:26:26PM +0100, Greg Kroah-Hartman wrote: > > > On Tue, Feb 27, 2024 at 02:18:51PM +0100, Carlos López wrote: > > > > On 25/2/24 9:16, Greg Kroah-Hartman wrote: > > > > > There is no actual issue right now because we have another check > > > > > afterwards and the out-of-bounds read is not being performed. In > > > > > any case it's better code with this fixed, hence the proposed > > > > > change. > > > > > > > > Given that there is no actual security issue this looks more like a > > > > hardening, and thus not deserving of a CVE, no? > > > > > > This was a tricky one, I think it's needed as we do not know how people > > > are really using these macros, right? If the PCI maintainer agrees (on > > > the cc:), I'll be glad to revoke it, it's their call. > > > > 09cc90063240 ("PCI: Introduce pci_dev_for_each_resource()") added > > pci_dev_for_each_resource(), which expands to: > > > > for (...; res = (&(dev)->resource[(bar)]), bar < PCI_NUM_RESOURCES; ...) > > > > We compute "res" before the bounds-check of "bar", so the pointer may > > be out-of-bounds, but the body of the pci_dev_for_each_resource() loop > > is never executed with that out-of-bounds value. > > > > So I don't think this is a security issue, no matter how > > pci_dev_for_each_resource() is used, unless the mere presence of an > > invalid address in a register is an issue. > > Ah, yeah, now I remember, stuff like this was fixed up in other loops as > just reading off into the wild can be a speculation issue and so we had > to fix up a bunch of places in the kernel where we did have "invalid > data" in a register. The code didn't use that, but the processor would > fetch from there, and boom, speculation mess. There's a whole research > paper published on this type of thing somewhere... > > So let's keep this as a CVE unless someone really doesn't want it marked > as such. Again, it is a "weakness that is fixed" in the kernel, and > because of that, a CVE can be allocated for it. Sounds good, I'm happy to have it as a CVE. Thanks for the speculation details; I'm certainly not an expert on that. Bjorn