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Subject[PATCH 3.10 21/46] IB/umad: Fix use-after-free on close
Date
3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bvanassche@acm.org>

commit 60e1751cb52cc6d1ae04b6bd3c2b96e770b5823f upstream.

Avoid that closing /dev/infiniband/umad<n> or /dev/infiniband/issm<n>
triggers a use-after-free. __fput() invokes f_op->release() before it
invokes cdev_put(). Make sure that the ib_umad_device structure is
freed by the cdev_put() call instead of f_op->release(). This avoids
that changing the port mode from IB into Ethernet and back to IB
followed by restarting opensmd triggers the following kernel oops:

general protection fault: 0000 [#1] PREEMPT SMP
RIP: 0010:[<ffffffff810cc65c>] [<ffffffff810cc65c>] module_put+0x2c/0x170
Call Trace:
[<ffffffff81190f20>] cdev_put+0x20/0x30
[<ffffffff8118e2ce>] __fput+0x1ae/0x1f0
[<ffffffff8118e35e>] ____fput+0xe/0x10
[<ffffffff810723bc>] task_work_run+0xac/0xe0
[<ffffffff81002a9f>] do_notify_resume+0x9f/0xc0
[<ffffffff814b8398>] int_signal+0x12/0x17

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=75051
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/infiniband/core/user_mad.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)

--- a/drivers/infiniband/core/user_mad.c
+++ b/drivers/infiniband/core/user_mad.c
@@ -98,7 +98,7 @@ struct ib_umad_port {

struct ib_umad_device {
int start_port, end_port;
- struct kref ref;
+ struct kobject kobj;
struct ib_umad_port port[0];
};

@@ -134,14 +134,18 @@ static DECLARE_BITMAP(dev_map, IB_UMAD_M
static void ib_umad_add_one(struct ib_device *device);
static void ib_umad_remove_one(struct ib_device *device);

-static void ib_umad_release_dev(struct kref *ref)
+static void ib_umad_release_dev(struct kobject *kobj)
{
struct ib_umad_device *dev =
- container_of(ref, struct ib_umad_device, ref);
+ container_of(kobj, struct ib_umad_device, kobj);

kfree(dev);
}

+static struct kobj_type ib_umad_dev_ktype = {
+ .release = ib_umad_release_dev,
+};
+
static int hdr_size(struct ib_umad_file *file)
{
return file->use_pkey_index ? sizeof (struct ib_user_mad_hdr) :
@@ -812,7 +816,7 @@ static int ib_umad_open(struct inode *in
goto out;
}

- kref_get(&port->umad_dev->ref);
+ kobject_get(&port->umad_dev->kobj);

out:
mutex_unlock(&port->file_mutex);
@@ -851,7 +855,7 @@ static int ib_umad_close(struct inode *i
mutex_unlock(&file->port->file_mutex);

kfree(file);
- kref_put(&dev->ref, ib_umad_release_dev);
+ kobject_put(&dev->kobj);

return 0;
}
@@ -902,7 +906,7 @@ static int ib_umad_sm_open(struct inode
if (ret)
goto err_clr_sm_cap;

- kref_get(&port->umad_dev->ref);
+ kobject_get(&port->umad_dev->kobj);

return 0;

@@ -932,7 +936,7 @@ static int ib_umad_sm_close(struct inode

up(&port->sm_sem);

- kref_put(&port->umad_dev->ref, ib_umad_release_dev);
+ kobject_put(&port->umad_dev->kobj);

return ret;
}
@@ -1000,6 +1004,7 @@ static int find_overflow_devnum(void)
}

static int ib_umad_init_port(struct ib_device *device, int port_num,
+ struct ib_umad_device *umad_dev,
struct ib_umad_port *port)
{
int devnum;
@@ -1032,6 +1037,7 @@ static int ib_umad_init_port(struct ib_d

cdev_init(&port->cdev, &umad_fops);
port->cdev.owner = THIS_MODULE;
+ port->cdev.kobj.parent = &umad_dev->kobj;
kobject_set_name(&port->cdev.kobj, "umad%d", port->dev_num);
if (cdev_add(&port->cdev, base, 1))
goto err_cdev;
@@ -1050,6 +1056,7 @@ static int ib_umad_init_port(struct ib_d
base += IB_UMAD_MAX_PORTS;
cdev_init(&port->sm_cdev, &umad_sm_fops);
port->sm_cdev.owner = THIS_MODULE;
+ port->sm_cdev.kobj.parent = &umad_dev->kobj;
kobject_set_name(&port->sm_cdev.kobj, "issm%d", port->dev_num);
if (cdev_add(&port->sm_cdev, base, 1))
goto err_sm_cdev;
@@ -1143,7 +1150,7 @@ static void ib_umad_add_one(struct ib_de
if (!umad_dev)
return;

- kref_init(&umad_dev->ref);
+ kobject_init(&umad_dev->kobj, &ib_umad_dev_ktype);

umad_dev->start_port = s;
umad_dev->end_port = e;
@@ -1151,7 +1158,8 @@ static void ib_umad_add_one(struct ib_de
for (i = s; i <= e; ++i) {
umad_dev->port[i - s].umad_dev = umad_dev;

- if (ib_umad_init_port(device, i, &umad_dev->port[i - s]))
+ if (ib_umad_init_port(device, i, umad_dev,
+ &umad_dev->port[i - s]))
goto err;
}

@@ -1163,7 +1171,7 @@ err:
while (--i >= s)
ib_umad_kill_port(&umad_dev->port[i - s]);

- kref_put(&umad_dev->ref, ib_umad_release_dev);
+ kobject_put(&umad_dev->kobj);
}

static void ib_umad_remove_one(struct ib_device *device)
@@ -1177,7 +1185,7 @@ static void ib_umad_remove_one(struct ib
for (i = 0; i <= umad_dev->end_port - umad_dev->start_port; ++i)
ib_umad_kill_port(&umad_dev->port[i]);

- kref_put(&umad_dev->ref, ib_umad_release_dev);
+ kobject_put(&umad_dev->kobj);
}

static char *umad_devnode(struct device *dev, umode_t *mode)



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