[3.8.y.z extended stable] Patch "IB/umad: Fix error handling" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    IB/umad: Fix error handling

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.27.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 7756e3eefb5d065aa6ff35309f4b9c56e30a3553 Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche at acm.org>
Date: Tue, 20 May 2014 10:33:41 +0200
Subject: IB/umad: Fix error handling

commit 8ec0a0e6b58218bdc1db91dd70ebfcd6ad8dd6cd upstream.

Avoid leaking a kref count in ib_umad_open() if port->ib_dev == NULL
or if nonseekable_open() fails.

Avoid leaking a kref count, that sm_sem is kept down and also that the
IB_PORT_SM capability mask is not cleared in ib_umad_sm_open() if
nonseekable_open() fails.

Since container_of() never returns NULL, remove the code that tests
whether container_of() returns NULL.

Moving the kref_get() call from the start of ib_umad_*open() to the
end is safe since it is the responsibility of the caller of these
functions to ensure that the cdev pointer remains valid until at least
when these functions return.

Signed-off-by: Bart Van Assche <bvanassche at acm.org>

[ydroneaud at opteya.com: rework a bit to reduce the amount of code changed]

Signed-off-by: Yann Droneaud <ydroneaud at opteya.com>

[ nonseekable_open() can't actually fail, but....  - Roland ]

Signed-off-by: Roland Dreier <roland at purestorage.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/infiniband/core/user_mad.c | 49 +++++++++++++++++++++-----------------
 1 file changed, 27 insertions(+), 22 deletions(-)

diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c
index f0d588f..9bdf576 100644
--- a/drivers/infiniband/core/user_mad.c
+++ b/drivers/infiniband/core/user_mad.c
@@ -780,27 +780,19 @@ static int ib_umad_open(struct inode *inode, struct file *filp)
 {
 	struct ib_umad_port *port;
 	struct ib_umad_file *file;
-	int ret;
+	int ret = -ENXIO;

 	port = container_of(inode->i_cdev, struct ib_umad_port, cdev);
-	if (port)
-		kref_get(&port->umad_dev->ref);
-	else
-		return -ENXIO;

 	mutex_lock(&port->file_mutex);

-	if (!port->ib_dev) {
-		ret = -ENXIO;
+	if (!port->ib_dev)
 		goto out;
-	}

+	ret = -ENOMEM;
 	file = kzalloc(sizeof *file, GFP_KERNEL);
-	if (!file) {
-		kref_put(&port->umad_dev->ref, ib_umad_release_dev);
-		ret = -ENOMEM;
+	if (!file)
 		goto out;
-	}

 	mutex_init(&file->mutex);
 	spin_lock_init(&file->send_lock);
@@ -814,6 +806,13 @@ static int ib_umad_open(struct inode *inode, struct file *filp)
 	list_add_tail(&file->port_list, &port->file_list);

 	ret = nonseekable_open(inode, filp);
+	if (ret) {
+		list_del(&file->port_list);
+		kfree(file);
+		goto out;
+	}
+
+	kref_get(&port->umad_dev->ref);

 out:
 	mutex_unlock(&port->file_mutex);
@@ -880,10 +879,6 @@ static int ib_umad_sm_open(struct inode *inode, struct file *filp)
 	int ret;

 	port = container_of(inode->i_cdev, struct ib_umad_port, sm_cdev);
-	if (port)
-		kref_get(&port->umad_dev->ref);
-	else
-		return -ENXIO;

 	if (filp->f_flags & O_NONBLOCK) {
 		if (down_trylock(&port->sm_sem)) {
@@ -898,17 +893,27 @@ static int ib_umad_sm_open(struct inode *inode, struct file *filp)
 	}

 	ret = ib_modify_port(port->ib_dev, port->port_num, 0, &props);
-	if (ret) {
-		up(&port->sm_sem);
-		goto fail;
-	}
+	if (ret)
+		goto err_up_sem;

 	filp->private_data = port;

-	return nonseekable_open(inode, filp);
+	ret = nonseekable_open(inode, filp);
+	if (ret)
+		goto err_clr_sm_cap;
+
+	kref_get(&port->umad_dev->ref);
+
+	return 0;
+
+err_clr_sm_cap:
+	swap(props.set_port_cap_mask, props.clr_port_cap_mask);
+	ib_modify_port(port->ib_dev, port->port_num, 0, &props);
+
+err_up_sem:
+	up(&port->sm_sem);

 fail:
-	kref_put(&port->umad_dev->ref, ib_umad_release_dev);
 	return ret;
 }

--
1.9.1