From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D082C433EF for ; Thu, 11 Nov 2021 16:04:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5828A61247 for ; Thu, 11 Nov 2021 16:04:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234107AbhKKQHN (ORCPT ); Thu, 11 Nov 2021 11:07:13 -0500 Received: from smtp1.axis.com ([195.60.68.17]:62896 "EHLO smtp1.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232033AbhKKQHI (ORCPT ); Thu, 11 Nov 2021 11:07:08 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; q=dns/txt; s=axis-central1; t=1636646660; x=1668182660; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=0i1LfHXs6uH2x7I8DD0PdVPydkm4E1YEPDn4tVDfrSs=; b=CNqYbl1pjo4/CBTQ2RMkkq5tAVBnsLApnCH55T0DUuxY9gSoPt9HqbyK fPuS9GE4elGJzQSqhwWulk6dEa2xoa8W388A9XQlaHCs05Q+x2xC41xmo 3pigNtWGvGEIEnmlDpZJ63iaKF8qrYfZHrFJ6Lx1tzh1vlvuh9oP3msdb RhM3lgymNGfq4VfDiZ5de8kfhvebv1QHX7dD2kwvZZv3oElehh5ulxML8 rpO3FPpkuHMtQkbpkiZ0U4sDlDzi8H70fx27bWASbhbx2zMYW2jIZUFOj 0hDtFfaS1FRooRAhSx0Yn2h8RvAi2NUl6E0dVYB3xtFY3oFyEpDk1FIeG w==; From: Vincent Whitchurch To: , , CC: , , , , , , Vincent Whitchurch Subject: [PATCH v2 1/2] i2c: virtio: disable timeout handling Date: Thu, 11 Nov 2021 17:04:11 +0100 Message-ID: <20211111160412.11980-2-vincent.whitchurch@axis.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20211111160412.11980-1-vincent.whitchurch@axis.com> References: <20211111160412.11980-1-vincent.whitchurch@axis.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If a timeout is hit, it can result is incorrect data on the I2C bus and/or memory corruptions in the guest since the device can still be operating on the buffers it was given while the guest has freed them. Here is, for example, the start of a slub_debug splat which was triggered on the next transfer after one transfer was forced to timeout by setting a breakpoint in the backend (rust-vmm/vhost-device): BUG kmalloc-1k (Not tainted): Poison overwritten First byte 0x1 instead of 0x6b Allocated in virtio_i2c_xfer+0x65/0x35c age=350 cpu=0 pid=29 __kmalloc+0xc2/0x1c9 virtio_i2c_xfer+0x65/0x35c __i2c_transfer+0x429/0x57d i2c_transfer+0x115/0x134 i2cdev_ioctl_rdwr+0x16a/0x1de i2cdev_ioctl+0x247/0x2ed vfs_ioctl+0x21/0x30 sys_ioctl+0xb18/0xb41 Freed in virtio_i2c_xfer+0x32e/0x35c age=244 cpu=0 pid=29 kfree+0x1bd/0x1cc virtio_i2c_xfer+0x32e/0x35c __i2c_transfer+0x429/0x57d i2c_transfer+0x115/0x134 i2cdev_ioctl_rdwr+0x16a/0x1de i2cdev_ioctl+0x247/0x2ed vfs_ioctl+0x21/0x30 sys_ioctl+0xb18/0xb41 There is no simple fix for this (the driver would have to always create bounce buffers and hold on to them until the device eventually returns the buffers), so just disable the timeout support for now. Fixes: 3cfc88380413d20f ("i2c: virtio: add a virtio i2c frontend driver") Acked-by: Jie Deng Signed-off-by: Vincent Whitchurch --- drivers/i2c/busses/i2c-virtio.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/drivers/i2c/busses/i2c-virtio.c b/drivers/i2c/busses/i2c-virtio.c index f10a603b13fb..7b2474e6876f 100644 --- a/drivers/i2c/busses/i2c-virtio.c +++ b/drivers/i2c/busses/i2c-virtio.c @@ -106,11 +106,10 @@ static int virtio_i2c_prepare_reqs(struct virtqueue *vq, static int virtio_i2c_complete_reqs(struct virtqueue *vq, struct virtio_i2c_req *reqs, - struct i2c_msg *msgs, int num, - bool timedout) + struct i2c_msg *msgs, int num) { struct virtio_i2c_req *req; - bool failed = timedout; + bool failed = false; unsigned int len; int i, j = 0; @@ -132,7 +131,7 @@ static int virtio_i2c_complete_reqs(struct virtqueue *vq, j++; } - return timedout ? -ETIMEDOUT : j; + return j; } static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, @@ -141,7 +140,6 @@ static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, struct virtio_i2c *vi = i2c_get_adapdata(adap); struct virtqueue *vq = vi->vq; struct virtio_i2c_req *reqs; - unsigned long time_left; int count; reqs = kcalloc(num, sizeof(*reqs), GFP_KERNEL); @@ -164,11 +162,9 @@ static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, reinit_completion(&vi->completion); virtqueue_kick(vq); - time_left = wait_for_completion_timeout(&vi->completion, adap->timeout); - if (!time_left) - dev_err(&adap->dev, "virtio i2c backend timeout.\n"); + wait_for_completion(&vi->completion); - count = virtio_i2c_complete_reqs(vq, reqs, msgs, count, !time_left); + count = virtio_i2c_complete_reqs(vq, reqs, msgs, count); err_free: kfree(reqs); -- 2.28.0