[PATCH 6.1 0716/1146] ocxl: fix pci device refcount leak when calling get_function_0()

Greg Kroah-Hartman
2022-12-28T16:27:31Z

From: Yang Yingliang <yangyingliang@huawei.com>

[ Upstream commit 27158c72678b39ee01cc01de1aba6b51c71abe2f ]

get_function_0() calls pci_get_domain_bus_and_slot(), as comment
says, it returns a pci device with refcount increment, so after
using it, pci_dev_put() needs be called.

Get the device reference when get_function_0() is not called, so
pci_dev_put() can be called in the error path and callers
unconditionally. And add comment above get_dvsec_vendor0() to tell
callers to call pci_dev_put().

Fixes: 87db7579ebd5 ("ocxl: control via sysfs whether the FPGA is reloaded on a link reset")
Suggested-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Acked-by: Andrew Donnellan <ajd@linux.ibm.com>
Link: https://lore.kernel.org/r/20221121154339.4088935-1-yangyingliang@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/misc/ocxl/config.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/config.c b/drivers/misc/ocxl/config.c
index e401a51596b9..92ab49705f64 100644
--- a/drivers/misc/ocxl/config.c
+++ b/drivers/misc/ocxl/config.c
@@ -193,6 +193,18 @@ static int read_dvsec_vendor(struct pci_dev *dev)
return 0;
}

+/**
+ * get_dvsec_vendor0() - Find a related PCI device (function 0)
+ * @dev: PCI device to match
+ * @dev0: The PCI device (function 0) found
+ * @out_pos: The position of PCI device (function 0)
+ *
+ * Returns 0 on success, negative on failure.
+ *
+ * NOTE: If it's successful, the reference of dev0 is increased,
+ * so after using it, the callers must call pci_dev_put() to give
+ * up the reference.
+ */
static int get_dvsec_vendor0(struct pci_dev *dev, struct pci_dev **dev0,
int *out_pos)
{
@@ -202,10 +214,14 @@ static int get_dvsec_vendor0(struct pci_dev *dev, struct pci_dev **dev0,
dev = get_function_0(dev);
if (!dev)
return -1;
+ } else {
+ dev = pci_dev_get(dev);
}
pos = find_dvsec(dev, OCXL_DVSEC_VENDOR_ID);
- if (!pos)
+ if (!pos) {
+ pci_dev_put(dev);
return -1;
+ }
*dev0 = dev;
*out_pos = pos;
return 0;
@@ -222,6 +238,7 @@ int ocxl_config_get_reset_reload(struct pci_dev *dev, int *val)

pci_read_config_dword(dev0, pos + OCXL_DVSEC_VENDOR_RESET_RELOAD,
&reset_reload);
+ pci_dev_put(dev0);
*val = !!(reset_reload & BIT(0));
return 0;
}
@@ -243,6 +260,7 @@ int ocxl_config_set_reset_reload(struct pci_dev *dev, int val)
reset_reload &= ~BIT(0);
pci_write_config_dword(dev0, pos + OCXL_DVSEC_VENDOR_RESET_RELOAD,
reset_reload);
+ pci_dev_put(dev0);
return 0;
}

--
2.35.1