staging: gasket: Fix mapping refcnt leak when put attribute fails

[ Upstream commit 57a66838e1494cd881b7f4e110ec685736e8e3ca ]

gasket_sysfs_put_attr() invokes get_mapping(), which returns a reference
of the specified gasket_sysfs_mapping object to "mapping" with increased
refcnt.

When gasket_sysfs_put_attr() returns, local variable "mapping" becomes
invalid, so the refcount should be decreased to keep refcount balanced.

The reference counting issue happens in one path of
gasket_sysfs_put_attr(). When mapping attribute is unknown, the function
forgets to decrease the refcnt increased by get_mapping(), causing a
refcnt leak.

Fix this issue by calling put_mapping() when put attribute fails due to
unknown attribute.

Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Link: https://lore.kernel.org/r/1587618895-13660-1-git-send-email-xiyuyang19@fudan.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/staging/gasket/gasket_sysfs.c b/drivers/staging/gasket/gasket_sysfs.c
index 5f0e089..ad852ea 100644 (file)
--- a/drivers/staging/gasket/gasket_sysfs.c
+++ b/drivers/staging/gasket/gasket_sysfs.c
@@ -339,6 +339,7 @@ void gasket_sysfs_put_attr(struct device *device,
 
        dev_err(device, "Unable to put unknown attribute: %s\n",
                attr->attr.attr.name);
+       put_mapping(mapping);
 }
 EXPORT_SYMBOL(gasket_sysfs_put_attr);