linux-kernel - [PATCH] media: cobalt: fix null-ptr-deref when there is no PCI bridge

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Message-Id: <20210424005206.261622-1-ztong0001@gmail.com>
Date:   Fri, 23 Apr 2021 20:52:06 -0400
From:   Tong Zhang <ztong0001@...il.com>
To:     Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Tong Zhang <ztong0001@...il.com>
Subject: [PATCH] media: cobalt: fix null-ptr-deref when there is no PCI bridge

the PCI bridge might be NULL, so we'd better check before use it

[    1.870569] RIP: 0010:pcie_bus_link_get_lanes.isra.0+0x26/0x59 [cobalt]
[    1.875880] Call Trace:
[    1.876013]  cobalt_probe.cold+0x1be/0xc11 [cobalt]
[    1.876683]  pci_device_probe+0x10f/0x1c0

Signed-off-by: Tong Zhang <ztong0001@...il.com>
---
 drivers/media/pci/cobalt/cobalt-driver.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/media/pci/cobalt/cobalt-driver.c b/drivers/media/pci/cobalt/cobalt-driver.c
index 0695078ef812..5687ed4869ac 100644
--- a/drivers/media/pci/cobalt/cobalt-driver.c
+++ b/drivers/media/pci/cobalt/cobalt-driver.c
@@ -189,6 +189,8 @@ void cobalt_pcie_status_show(struct cobalt *cobalt)
 	u32 capa;
 	u16 stat, ctrl;
 
+	if (!pci_bus_dev)
+		return;
 	if (!pci_is_pcie(pci_dev) || !pci_is_pcie(pci_bus_dev))
 		return;
 
@@ -247,6 +249,8 @@ static unsigned pcie_bus_link_get_lanes(struct cobalt *cobalt)
 	struct pci_dev *pci_dev = cobalt->pci_dev->bus->self;
 	u32 link;
 
+	if (!pci_dev)
+		return 0;
 	if (!pci_is_pcie(pci_dev))
 		return 0;
 	pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &link);
-- 
2.25.1