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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: yuanxzhang@fudan.edu.cn, kjlu@umn.edu,
	Xiyu Yang <xiyuyang19@fudan.edu.cn>,
	Xin Tan <tanxin.ctf@gmail.com>
Subject: [PATCH] staging: gasket: Fix mapping refcnt leak when register/store fails
Date: Thu, 23 Apr 2020 13:15:40 +0800	[thread overview]
Message-ID: <1587618941-13718-1-git-send-email-xiyuyang19@fudan.edu.cn> (raw)

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

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

The reference counting issue happens in one exception handling path of
gasket_sysfs_register_store(). When gasket_dev is NULL, the function
forgets to decrease the refcnt increased by get_mapping(), causing a
refcnt leak.

Fix this issue by calling put_mapping() when gasket_dev is NULL.

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 f24edc38c27b..b4aa8c2ba2c0 100644
--- a/drivers/staging/gasket/gasket_sysfs.c
+++ b/drivers/staging/gasket/gasket_sysfs.c
@@ -374,6 +374,7 @@ ssize_t gasket_sysfs_register_store(struct device *device,
 	gasket_dev = mapping->gasket_dev;
 	if (!gasket_dev) {
 		dev_err(device, "Device driver may have been removed\n");
+		put_mapping(mapping);
 		return 0;
 	}
 
-- 
2.7.4


WARNING: multiple messages have this Message-ID (diff)
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 register/store fails
Date: Thu, 23 Apr 2020 13:15:40 +0800	[thread overview]
Message-ID: <1587618941-13718-1-git-send-email-xiyuyang19@fudan.edu.cn> (raw)

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

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

The reference counting issue happens in one exception handling path of
gasket_sysfs_register_store(). When gasket_dev is NULL, the function
forgets to decrease the refcnt increased by get_mapping(), causing a
refcnt leak.

Fix this issue by calling put_mapping() when gasket_dev is NULL.

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 f24edc38c27b..b4aa8c2ba2c0 100644
--- a/drivers/staging/gasket/gasket_sysfs.c
+++ b/drivers/staging/gasket/gasket_sysfs.c
@@ -374,6 +374,7 @@ ssize_t gasket_sysfs_register_store(struct device *device,
 	gasket_dev = mapping->gasket_dev;
 	if (!gasket_dev) {
 		dev_err(device, "Device driver may have been removed\n");
+		put_mapping(mapping);
 		return 0;
 	}
 
-- 
2.7.4

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             reply	other threads:[~2020-04-23  5:17 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-23  5:15 Xiyu Yang [this message]
2020-04-23  5:15 ` [PATCH] staging: gasket: Fix mapping refcnt leak when register/store fails Xiyu Yang

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