linux-kernel - [PATCH 1/1] PCI/MSI: add NULL check before use of msi

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Date:   Tue, 16 Jan 2018 18:15:47 +0900
From:   Hiraku Toyooka <hiraku.toyooka@...ertrust.co.jp>
To:     bhelgaas@...gle.com
Cc:     Hiraku Toyooka <hiraku.toyooka@...ertrust.co.jp>,
        linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, hongxing.zhu@....com,
        l.stach@...gutronix.de, jingoohan1@...il.com,
        Joao.Pinto@...opsys.com, lorenzo.pieralisi@....com,
        linux@...linux.org.uk, will.deacon@....com
Subject: [PATCH 1/1] PCI/MSI: add NULL check before use of msi_desc

On starting kdump kernel in arm, arm64 and powerpc, chip->irq_mask() is
called for each irq_data to mask interrupts. For MSI irqs,
pci_msi_mask_irq() is called even when the irq_data doesn't have a link
to msi_desc. This results in a NULL pointer dereference.

This patch fixes the above error by avoiding NULL msi_desc use.

Signed-off-by: Hiraku Toyooka <hiraku.toyooka@...ertrust.co.jp>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Richard Zhu <hongxing.zhu@....com>
Cc: Lucas Stach <l.stach@...gutronix.de>
Cc: Jingoo Han <jingoohan1@...il.com>
Cc: Joao Pinto <Joao.Pinto@...opsys.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc: Russell King <linux@...linux.org.uk>
Cc: Will Deacon <will.deacon@....com>
---
 drivers/pci/msi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index e066071..a6ee274 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -227,6 +227,9 @@ static void msi_set_mask_bit(struct irq_data *data, u32 flag)
 {
 	struct msi_desc *desc = irq_data_get_msi_desc(data);
 
+	if (!desc)
+		return;
+
 	if (desc->msi_attrib.is_msix) {
 		msix_mask_irq(desc, flag);
 		readl(desc->mask_base);		/* Flush write to device */
-- 
2.7.4