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nfc: replace improper check device_is_registered() in netlink related functions

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The device_is_registered() in nfc core is used to check whether
nfc device is registered in netlink related functions such as
nfc_fw_download(), nfc_dev_up() and so on. Although device_is_registered()
is protected by device_lock, there is still a race condition between
device_del() and device_is_registered(). The root cause is that
kobject_del() in device_del() is not protected by device_lock.

   (cleanup task)         |     (netlink task)
                          |
nfc_unregister_device     | nfc_fw_download
 device_del               |  device_lock
  ...                     |   if (!device_is_registered)//(1)
  kobject_del//(2)        |   ...
 ...                      |  device_unlock

The device_is_registered() returns the value of state_in_sysfs and
the state_in_sysfs is set to zero in kobject_del(). If we pass check in
position (1), then set zero in position (2). As a result, the check
in position (1) is useless.

This patch uses bool variable instead of device_is_registered() to judge
whether the nfc device is registered, which is well synchronized.

Fixes: 3e256b8f8d ("NFC: add nfc subsystem core")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Duoming Zhou 2022-04-29 20:45:50 +08:00 committed by David S. Miller
parent 47f753c110
commit da5c0f1192
1 changed files with 14 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
net/nfc/core.c
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@ -38,7 +38,7 @@ int nfc_fw_download(struct nfc_dev *dev, const char *firmware_name)
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
goto error;
}
@ -94,7 +94,7 @@ int nfc_dev_up(struct nfc_dev *dev)
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
goto error;
}
@ -142,7 +142,7 @@ int nfc_dev_down(struct nfc_dev *dev)
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
goto error;
}
@ -207,7 +207,7 @@ int nfc_start_poll(struct nfc_dev *dev, u32 im_protocols, u32 tm_protocols)
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
goto error;
}
@ -246,7 +246,7 @@ int nfc_stop_poll(struct nfc_dev *dev)
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
goto error;
}
@ -291,7 +291,7 @@ int nfc_dep_link_up(struct nfc_dev *dev, int target_index, u8 comm_mode)
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
goto error;
}
@ -335,7 +335,7 @@ int nfc_dep_link_down(struct nfc_dev *dev)
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
goto error;
}
@ -401,7 +401,7 @@ int nfc_activate_target(struct nfc_dev *dev, u32 target_idx, u32 protocol)
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
goto error;
}
@ -448,7 +448,7 @@ int nfc_deactivate_target(struct nfc_dev *dev, u32 target_idx, u8 mode)
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
goto error;
}
@ -495,7 +495,7 @@ int nfc_data_exchange(struct nfc_dev *dev, u32 target_idx, struct sk_buff *skb,
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
kfree_skb(skb);
goto error;
@ -552,7 +552,7 @@ int nfc_enable_se(struct nfc_dev *dev, u32 se_idx)
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
goto error;
}
@ -601,7 +601,7 @@ int nfc_disable_se(struct nfc_dev *dev, u32 se_idx)
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
if (dev->shutting_down) {
rc = -ENODEV;
goto error;
}
@ -1134,6 +1134,7 @@ int nfc_register_device(struct nfc_dev *dev)
dev->rfkill = NULL;
}
}
dev->shutting_down = false;
device_unlock(&dev->dev);
rc = nfc_genl_device_added(dev);
@ -1166,12 +1167,10 @@ void nfc_unregister_device(struct nfc_dev *dev)
rfkill_unregister(dev->rfkill);
rfkill_destroy(dev->rfkill);
}
dev->shutting_down = true;
device_unlock(&dev->dev);
if (dev->ops->check_presence) {
device_lock(&dev->dev);
dev->shutting_down = true;
device_unlock(&dev->dev);
del_timer_sync(&dev->check_pres_timer);
cancel_work_sync(&dev->check_pres_work);
}