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Sun, 8 Apr 2018 20:28:35 -0400 From: Sasha Levin To: "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" CC: Christoph Hellwig , Bjorn Helgaas , Sasha Levin Subject: [PATCH AUTOSEL for 4.9 076/293] PCI: Protect pci_error_handlers->reset_notify() usage with device_lock() Thread-Topic: [PATCH AUTOSEL for 4.9 076/293] PCI: Protect pci_error_handlers->reset_notify() usage with device_lock() Thread-Index: AQHTz5kKG60HtASDM0iklGqio8LNWA== Date: Mon, 9 Apr 2018 00:23:53 +0000 Message-ID: <20180409002239.163177-76-alexander.levin@microsoft.com> References: <20180409002239.163177-1-alexander.levin@microsoft.com> In-Reply-To: <20180409002239.163177-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR2101MB0807;7:Fn87e1a715CHmp0gqUpjhhY2mHMK+u9wBnWMBnVyAEb1riErPLZIKfVSuM6BDJ2CU+dFXuNXs6YxusPfr76+F2pmLe9prDKwWiR/LcDnlGHMLGaj3P/coh2yN1/1WN513j+OIHIqpyfPeKai9MFDE4HnByy+FozOwFU/X1seLO9M0bdkwuVgKKIO2K4pen58yQS57Em95jhCz7PgSwp5cNKRN9zfd/RflVkRQh6EHnwSXfv8M/43I0AGPy7SoiMJ;20:T6tjxadHw764NbTsBdN9JrZ3ehrZ+hf8WFb8gguBIlPadnlqRbNngYsjZU8bXg/+F6v2Gm9e84FxPV0q2S/YUmvcaVxWSoOgrjV6/na3HhjYqlLgSq87x1UlhNdtD5r9XaUai3DivUKKJOd9C0d1UxyXkXivOpqf8YaSztIYJS8= x-ms-office365-filtering-ht: Tenant X-MS-Office365-Filtering-Correlation-Id: 205d5a17-3136-4416-19dd-08d59db0d10d x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7193020);SRVR:DM5PR2101MB0807; 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x-microsoft-antispam-message-info: MeC3bmhR6zmLJerMAUed4q8fg0vbtb/2GFdEb6rSY2B8f5o1ibxevspPSqoB4zS9L1Fq5QX/OJpxY9EIBTuQcsT+z+G1r+xw9xlU0+vy08mrZZqkGt1iCspUuwJKOOtb9LX+kGifRaDXTztEwv0VLTnfSyaMGI/eYSiwvcJkdG/j0TeDi4YLTXXUH1V2BNHAhwiPeEBMUWgd6PMr25LSNZ0HuPcbMrYFrbgFqzZmW6grymB5AV+YeoUeU6P+g1ZGvnKVdNvnNATLWZkXacqrF4/ttMF+L/CuSbaqI81UWjj/JCN0A52gTRjoFMnfU/y1XFDbRPB6GuaBpBN+GkvqIHGmW5lE1R4B4nxoX3Vnu6scZ69ZEXf/dFMmBxMBgZWCMbJA9MzdYFB4UXOkqh1oB1+em5C4alW3QsISEU5KtXQ= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 205d5a17-3136-4416-19dd-08d59db0d10d X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Apr 2018 00:23:53.5812 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB0807 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Christoph Hellwig [ Upstream commit b014e96d1abbd67404bbe2018937b46466299e9e ] Every method in struct device_driver or structures derived from it like struct pci_driver MUST provide exclusion vs the driver's ->remove() method, usually by using device_lock(). Protect use of pci_error_handlers->reset_notify() by holding the device lock while calling it. Note: - pci_dev_lock() calls device_lock() in addition to blocking user-space config accesses. - pci_err_handlers->reset_notify() is used inside pci_dev_save_and_disable() and pci_dev_restore(). We could hold the device lock directly in pci_reset_notify(), but we expand the region since we have several calls following each other. Without this, ->reset_notify() may race with ->remove() calls, which can be easily triggered in NVMe. [bhelgaas: changelog, add pci_reset_notify() comment] [bhelgaas: fold in fix from Dan Carpenter : http://lkml.kernel.org/r/20170701135323.x5vaj4e2wcs2mcro@mwanda] Link: http://lkml.kernel.org/r/20170601111039.8913-2-hch@lst.de Reported-by: Rakesh Pandit Tested-by: Rakesh Pandit Signed-off-by: Christoph Hellwig Signed-off-by: Bjorn Helgaas Signed-off-by: Sasha Levin --- drivers/pci/pci.c | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index a87c8e1aef68..774b0e2d117b 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4036,6 +4036,12 @@ static void pci_reset_notify(struct pci_dev *dev, bo= ol prepare) { const struct pci_error_handlers *err_handler =3D dev->driver ? dev->driver->err_handler : NULL; + + /* + * dev->driver->err_handler->reset_notify() is protected against + * races with ->remove() by the device lock, which must be held by + * the caller. + */ if (err_handler && err_handler->reset_notify) err_handler->reset_notify(dev, prepare); } @@ -4171,11 +4177,13 @@ int pci_reset_function(struct pci_dev *dev) if (rc) return rc; =20 + pci_dev_lock(dev); pci_dev_save_and_disable(dev); =20 - rc =3D pci_dev_reset(dev, 0); + rc =3D __pci_dev_reset(dev, 0); =20 pci_dev_restore(dev); + pci_dev_unlock(dev); =20 return rc; } @@ -4195,16 +4203,14 @@ int pci_try_reset_function(struct pci_dev *dev) if (rc) return rc; =20 - pci_dev_save_and_disable(dev); + if (!pci_dev_trylock(dev)) + return -EAGAIN; =20 - if (pci_dev_trylock(dev)) { - rc =3D __pci_dev_reset(dev, 0); - pci_dev_unlock(dev); - } else - rc =3D -EAGAIN; + pci_dev_save_and_disable(dev); + rc =3D __pci_dev_reset(dev, 0); + pci_dev_unlock(dev); =20 pci_dev_restore(dev); - return rc; } EXPORT_SYMBOL_GPL(pci_try_reset_function); @@ -4358,7 +4364,9 @@ static void pci_bus_save_and_disable(struct pci_bus *= bus) struct pci_dev *dev; =20 list_for_each_entry(dev, &bus->devices, bus_list) { + pci_dev_lock(dev); pci_dev_save_and_disable(dev); + pci_dev_unlock(dev); if (dev->subordinate) pci_bus_save_and_disable(dev->subordinate); } @@ -4373,7 +4381,9 @@ static void pci_bus_restore(struct pci_bus *bus) struct pci_dev *dev; =20 list_for_each_entry(dev, &bus->devices, bus_list) { + pci_dev_lock(dev); pci_dev_restore(dev); + pci_dev_unlock(dev); if (dev->subordinate) pci_bus_restore(dev->subordinate); } --=20 2.15.1