linux-kernel - [PATCH] pci: Warn if BME cannot be turned off during kexec

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200104225052.27275-1-deepa.kernel@gmail.com>
Date:   Sat,  4 Jan 2020 14:50:52 -0800
From:   Deepa Dinamani <deepa.kernel@...il.com>
To:     bhelgaas@...gle.com
Cc:     mika.westerberg@...ux.intel.com, alex.williamson@...hat.com,
        logang@...tatee.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] pci: Warn if BME cannot be turned off during kexec

BME not being off is a security risk, so for whatever
reason if we cannot disable it, print a warning.

Signed-off-by: Deepa Dinamani <deepa.kernel@...il.com>
---
 drivers/pci/pci-driver.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 0454ca0e4e3f..6c866a81f46c 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -491,8 +491,12 @@ static void pci_device_shutdown(struct device *dev)
 	 * If it is not a kexec reboot, firmware will hit the PCI
 	 * devices with big hammer and stop their DMA any way.
 	 */
-	if (kexec_in_progress && (pci_dev->current_state <= PCI_D3hot))
-		pci_clear_master(pci_dev);
+	if (kexec_in_progress) {
+		if (likely(pci_dev->current_state <= PCI_D3hot))
+			pci_clear_master(pci_dev);
+		else
+			dev_warn(dev, "Unable to turn off BME during kexec");
+	}
 }
 
 #ifdef CONFIG_PM
-- 
2.17.1