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From: Xiyu Yang <xiyuyang19@fudan.edu.cn>
To: Rob Springer <rspringer@google.com>,
	Todd Poynor <toddpoynor@google.com>,
	Ben Chan <benchan@chromium.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org
Cc: Xin Tan <tanxin.ctf@gmail.com>,
	yuanxzhang@fudan.edu.cn, kjlu@umn.edu,
	Xiyu Yang <xiyuyang19@fudan.edu.cn>
Subject: [PATCH] staging: gasket: Fix mapping refcnt leak when put attribute fails
Date: Thu, 23 Apr 2020 13:14:55 +0800
Message-ID: <1587618895-13660-1-git-send-email-xiyuyang19@fudan.edu.cn> (raw)

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>
---
 drivers/staging/gasket/gasket_sysfs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/staging/gasket/gasket_sysfs.c b/drivers/staging/gasket/gasket_sysfs.c
index a2d67c28f530..f24edc38c27b 100644
--- a/drivers/staging/gasket/gasket_sysfs.c
+++ b/drivers/staging/gasket/gasket_sysfs.c
@@ -340,6 +340,7 @@ 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);
 
-- 
2.7.4

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