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 09B4E3C2F; Wed, 21 Feb 2024 13:39:22 +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=1708522762; cv=none; b=TuOwWLokMfcuEvjOPQskDPrntQ5LR937wBbU1QXVwDdmEsTR1Y5/WCrxytSNsdE3xwdgQcpzzYRZlFNn0mcOCWKA+U//tcSg2Y23K++UdXRFFxsLh2siyqVfgg3poRDXVWmpMAiFsF4d2dcRGRItprLDQp+/mkY43LdgqJ1S/HA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708522762; c=relaxed/simple; bh=RhgcXt5gfpgENGg8aiTx+cM+L6LziPXTPL/3CCl/CyY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UeQeZp2fo4H3BoMwrH/6Dgp80HUf07yaYHENVx/yacawWd1Aw2Zu892CzjIsJXPpPz4JPEtpHUswlKDo2jOIAahLc94wEkXiYTV0akIsRsVo7rXOrIN/S92SjkfWM7PSQa6cEUJEVFugtHrfDerHgLpmtO1vs8eOh02iNE7ik8U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sO15zWTH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="sO15zWTH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6DA6FC43394; Wed, 21 Feb 2024 13:39:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1708522761; bh=RhgcXt5gfpgENGg8aiTx+cM+L6LziPXTPL/3CCl/CyY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sO15zWTHCFlsSF1t4ONDgWVtCct0IYprAkPY+beUL6ftSJ1B9s1kY2Dt6hBn3WuUF XmGjwagxLK2l08nPZXJfjZM3wVp0lqafSMlt83T4mXUHbf372Sh+6FPYW2lmNT6WwZ /Owd6waKWXLSEJ4KunAZm6JrVTR5XzJh1002slj8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Daniel Stodden , Bjorn Helgaas , Logan Gunthorpe , Dmitry Safonov , Sasha Levin Subject: [PATCH 5.15 250/476] PCI: switchtec: Fix stdev_release() crash after surprise hot remove Date: Wed, 21 Feb 2024 14:05:01 +0100 Message-ID: <20240221130017.100425375@linuxfoundation.org> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20240221130007.738356493@linuxfoundation.org> References: <20240221130007.738356493@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Stodden [ Upstream commit df25461119d987b8c81d232cfe4411e91dcabe66 ] A PCI device hot removal may occur while stdev->cdev is held open. The call to stdev_release() then happens during close or exit, at a point way past switchtec_pci_remove(). Otherwise the last ref would vanish with the trailing put_device(), just before return. At that later point in time, the devm cleanup has already removed the stdev->mmio_mrpc mapping. Also, the stdev->pdev reference was not a counted one. Therefore, in DMA mode, the iowrite32() in stdev_release() will cause a fatal page fault, and the subsequent dma_free_coherent(), if reached, would pass a stale &stdev->pdev->dev pointer. Fix by moving MRPC DMA shutdown into switchtec_pci_remove(), after stdev_kill(). Counting the stdev->pdev ref is now optional, but may prevent future accidents. Reproducible via the script at https://lore.kernel.org/r/20231113212150.96410-1-dns@arista.com Link: https://lore.kernel.org/r/20231122042316.91208-2-dns@arista.com Signed-off-by: Daniel Stodden Signed-off-by: Bjorn Helgaas Reviewed-by: Logan Gunthorpe Reviewed-by: Dmitry Safonov Signed-off-by: Sasha Levin --- drivers/pci/switch/switchtec.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c index d021ef3fb165..2a026183f06b 100644 --- a/drivers/pci/switch/switchtec.c +++ b/drivers/pci/switch/switchtec.c @@ -1250,13 +1250,6 @@ static void stdev_release(struct device *dev) { struct switchtec_dev *stdev = to_stdev(dev); - if (stdev->dma_mrpc) { - iowrite32(0, &stdev->mmio_mrpc->dma_en); - flush_wc_buf(stdev); - writeq(0, &stdev->mmio_mrpc->dma_addr); - dma_free_coherent(&stdev->pdev->dev, sizeof(*stdev->dma_mrpc), - stdev->dma_mrpc, stdev->dma_mrpc_dma_addr); - } kfree(stdev); } @@ -1300,7 +1293,7 @@ static struct switchtec_dev *stdev_create(struct pci_dev *pdev) return ERR_PTR(-ENOMEM); stdev->alive = true; - stdev->pdev = pdev; + stdev->pdev = pci_dev_get(pdev); INIT_LIST_HEAD(&stdev->mrpc_queue); mutex_init(&stdev->mrpc_mutex); stdev->mrpc_busy = 0; @@ -1334,6 +1327,7 @@ static struct switchtec_dev *stdev_create(struct pci_dev *pdev) return stdev; err_put: + pci_dev_put(stdev->pdev); put_device(&stdev->dev); return ERR_PTR(rc); } @@ -1586,6 +1580,18 @@ static int switchtec_init_pci(struct switchtec_dev *stdev, return 0; } +static void switchtec_exit_pci(struct switchtec_dev *stdev) +{ + if (stdev->dma_mrpc) { + iowrite32(0, &stdev->mmio_mrpc->dma_en); + flush_wc_buf(stdev); + writeq(0, &stdev->mmio_mrpc->dma_addr); + dma_free_coherent(&stdev->pdev->dev, sizeof(*stdev->dma_mrpc), + stdev->dma_mrpc, stdev->dma_mrpc_dma_addr); + stdev->dma_mrpc = NULL; + } +} + static int switchtec_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) { @@ -1645,6 +1651,9 @@ static void switchtec_pci_remove(struct pci_dev *pdev) ida_simple_remove(&switchtec_minor_ida, MINOR(stdev->dev.devt)); dev_info(&stdev->dev, "unregistered.\n"); stdev_kill(stdev); + switchtec_exit_pci(stdev); + pci_dev_put(stdev->pdev); + stdev->pdev = NULL; put_device(&stdev->dev); } -- 2.43.0