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 6F16A19ABC6; Mon, 18 May 2026 15:06:19 +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=1779116779; cv=none; b=bNv7pwZrTUN1PwBEthfP4L+qws9jqPYSTCG8Hyxe/YPSRMneBXetPy6QpF1PqBHbKxOyOafVfOnBe+MPcZqkeahDp6O1MHecvfz9QYlBn9zjEV3tsZO06QvVHvXXSgzo+3gAFsGdhxtzKF3BRl4VEHCg0lth2yan94dWLYc3qyI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779116779; c=relaxed/simple; bh=lATa/r0ZFjw8qqV79/ZQNsUYTNfLU6ueO04eOm44xtk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=K3AkOvMXfGzJ0cPxh88DXmKwo/ONU6pBfhO8NAZxfWO+gIqO+/98OEAWzZ/UmphHdGco4qOX4wr6PsEW+JhPUzDVCdQpF0lAvSHG/a8sJh6515QZ2ZitxuC9kVSZOutBDRL4px0ZyT25c7MxNueGu0bxyWq7ItfsKM0aIIB4vtI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tDSQU9Ik; 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="tDSQU9Ik" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E00FDC2BCB8; Mon, 18 May 2026 15:06:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1779116779; bh=lATa/r0ZFjw8qqV79/ZQNsUYTNfLU6ueO04eOm44xtk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tDSQU9Ik86VcwMW+OHuD9X8bUcZFMKMi5POlmSn6wCAMje+cG2xN9F5ScxYbZ44Wz IFSgolBsUDPX5yCAVN4Se9swKebpvd/NiVca7o8l8Ru8zBQm3lGzeTrDvhl9HEHIil VvznJgGdhRxmZIclUhXK9+bk1u+8EJO8A9rs3SHaKyaW7qNV/hMp9ufWvBtxT9NxOx djFk5yVSGOaKK2yhfahm434KPsSj44fYqB5YmENPlsA5Ab2WhGF8ilxVvKfiFE7cNH aLFKwscgEhqU6fenL2wkSK3V2ILiu+3H7S+ug519nIDIEpnLHgdxW1G6h3uhyO0Ks6 TLr9QYkQuPAeA== Date: Mon, 18 May 2026 16:06:11 +0100 From: Will Deacon To: Fredrik Markstrom Cc: Catalin Marinas , Shuah Khan , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Santosh Shilimkar , Olof Johansson , Tony Lindgren , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-perf-users@vger.kernel.org, Nicolas Pitre , Ivar Holmqvist , Malin Jonsson Subject: Re: [PATCH v2 0/3] arm64: perf: Skip device memory during user callchain unwinding Message-ID: References: <20260430-master-with-pfix-v3-v2-0-bd526ec04a75@est.tech> Precedence: bulk X-Mailing-List: linux-perf-users@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: <20260430-master-with-pfix-v3-v2-0-bd526ec04a75@est.tech> On Thu, Apr 30, 2026 at 12:55:12PM +0200, Fredrik Markstrom wrote: > Perf callchain unwinding follows userspace frame pointers via > copy_from_user. A corrupted or malicious frame pointer can point > into device I/O memory mapped into the process (e.g. via UIO or > /dev/mem), causing the kernel to read from MMIO regions in PMU > interrupt context. Such reads can have side effects on hardware > (clearing status registers, advancing FIFOs, triggering DMA) and > on arm64 can produce a synchronous external abort that panics the > kernel. Hmm, but why is unwinding special in this case? If userspace has access to sensitive MMIO/device mappings, it can presumably pass them to syscalls and trigger crashes all over the place? Will