From: Yicong Yang <yangyicong@hisilicon.com> stable inclusion from stable-4.19.247 commit aed6d4d519210c28817948f34c53b6e058e0456c category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5FNPY CVE: NA -------------------------------- [ Upstream commit a91ee0e9fca9d7501286cfbced9b30a33e52740a ] The sysfs sriov_numvfs_store() path acquires the device lock before the config space access lock: sriov_numvfs_store device_lock # A (1) acquire device lock sriov_configure vfio_pci_sriov_configure # (for example) vfio_pci_core_sriov_configure pci_disable_sriov sriov_disable pci_cfg_access_lock pci_wait_cfg # B (4) wait for dev->block_cfg_access == 0 Previously, pci_dev_lock() acquired the config space access lock before the device lock: pci_dev_lock pci_cfg_access_lock dev->block_cfg_access = 1 # B (2) set dev->block_cfg_access = 1 device_lock # A (3) wait for device lock Any path that uses pci_dev_lock(), e.g., pci_reset_function(), may deadlock with sriov_numvfs_store() if the operations occur in the sequence (1) (2) (3) (4). Avoid the deadlock by reversing the order in pci_dev_lock() so it acquires the device lock before the config space access lock, the same as the sriov_numvfs_store() path. [bhelgaas: combined and adapted commit log from Jay Zhou's independent subsequent posting: https://lore.kernel.org/r/20220404062539.1710-1-jianjay.zhou@huawei.com] Link: https://lore.kernel.org/linux-pci/1583489997-17156-1-git-send-email-yangyico... Also-posted-by: Jay Zhou <jianjay.zhou@huawei.com> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com> Signed-off-by: Laibin Qiu <qiulaibin@huawei.com> --- drivers/pci/pci.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index e74ebff1e29f..2020452d1f17 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4759,18 +4759,18 @@ static int pci_dev_reset_slot_function(struct pci_dev *dev, int probe) static void pci_dev_lock(struct pci_dev *dev) { - pci_cfg_access_lock(dev); /* block PM suspend, driver probe, etc. */ device_lock(&dev->dev); + pci_cfg_access_lock(dev); } /* Return 1 on successful lock, 0 on contention */ static int pci_dev_trylock(struct pci_dev *dev) { - if (pci_cfg_access_trylock(dev)) { - if (device_trylock(&dev->dev)) + if (device_trylock(&dev->dev)) { + if (pci_cfg_access_trylock(dev)) return 1; - pci_cfg_access_unlock(dev); + device_unlock(&dev->dev); } return 0; @@ -4778,8 +4778,8 @@ static int pci_dev_trylock(struct pci_dev *dev) static void pci_dev_unlock(struct pci_dev *dev) { - device_unlock(&dev->dev); pci_cfg_access_unlock(dev); + device_unlock(&dev->dev); } static void pci_dev_save_and_disable(struct pci_dev *dev) -- 2.25.1