From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.15]) (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 B265D5383; Wed, 9 Jul 2025 15:26:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752074785; cv=none; b=LVEr26Adw4lICpYv4u1lDRUvqj1m4NttpZ0IS3ShGrG8Qtt/a1iSXIYUTZLCLQ46ymFYKs9jfFYcTk4t+IDu7bK954V2egUgV+v5zNb1j3//MuGaf8tDS5pY+qOqaM4VSL+w7eI30IcPmHXEulKCowdh+QZv4/ZNHX7fBcxYJ/I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752074785; c=relaxed/simple; bh=I58dVPo5Wh3ABbjQx+DKjLaTOmLE+HHk0PL8WqsGQZ8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aG8JZTxER32UZ0gBPqIKgbWoYi0TOFY3EPIIQgB9xDJHDg87wOFrjJAmPSuhWmmll2zmxI+W8g/qxzlQZWOVbDE5uY2cegjsSyb5bLl83qp69yrkpprGvE/D8tz7UsbEQHiAR0DdeP1n/KVn/PNWCOCwTW5kVXkwtZrzldAp03w= ARC-Authentication-Results:i=1; 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X-CSE-ConnectionGUID: +v9JfkZ/RTCUgfYOA5Jueg== X-CSE-MsgGUID: gMRDtlp9T/eoMhs+0JUs3Q== X-IronPort-AV: E=McAfee;i="6800,10657,11489"; a="58006799" X-IronPort-AV: E=Sophos;i="6.16,298,1744095600"; d="scan'208";a="58006799" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jul 2025 08:26:22 -0700 X-CSE-ConnectionGUID: yinaxIZjTniveTWTvfRBgg== X-CSE-MsgGUID: N81UnTO1TJ6iwQMtIin03A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,298,1744095600"; d="scan'208";a="156370755" Received: from puneetse-mobl.amr.corp.intel.com (HELO [10.125.110.190]) ([10.125.110.190]) by fmviesa008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jul 2025 08:26:21 -0700 Message-ID: Date: Wed, 9 Jul 2025 08:29:57 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/1] iommu/sva: Invalidate KVA range on kernel TLB flush To: Lu Baolu , Joerg Roedel , Will Deacon , Robin Murphy , Kevin Tian , Jason Gunthorpe , Jann Horn , Vasant Hegde , Alistair Popple , Peter Zijlstra , Uladzislau Rezki , Jean-Philippe Brucker , Andy Lutomirski , "Tested-by : Yi Lai" Cc: iommu@lists.linux.dev, security@kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20250709062800.651521-1-baolu.lu@linux.intel.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/8/25 23:28, Lu Baolu wrote: > Modern IOMMUs often cache page table entries to optimize walk performance, > even for intermediate page table levels. If kernel page table mappings are > changed (e.g., by vfree()), but the IOMMU's internal caches retain stale > entries, Use-After-Free (UAF) vulnerability condition arises. If these > freed page table pages are reallocated for a different purpose, potentially > by an attacker, the IOMMU could misinterpret the new data as valid page > table entries. This allows the IOMMU to walk into attacker-controlled > memory, leading to arbitrary physical memory DMA access or privilege > escalation. The approach here is certainly conservative and simple. It's also not going to cause big problems on systems without fancy IOMMUs. But I am a _bit_ worried that it's _too_ conservative. The changelog talks about page table page freeing, but the actual code: > @@ -1540,6 +1541,7 @@ void flush_tlb_kernel_range(unsigned long start, unsigned long end) > kernel_tlb_flush_range(info); > > put_flush_tlb_info(); > + iommu_sva_invalidate_kva_range(start, end); > } is in a very generic TLB flushing spot that's used for a lot more than just freeing page tables. If the problem is truly limited to freeing page tables, it needs to be commented appropriately.