diff options
author | Duoming Zhou <duoming@zju.edu.cn> | 2022-04-29 15:45:50 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-05-12 13:23:44 +0300 |
commit | 85aecdef77f9c5b5c0d8988db6681960f0d46ab3 (patch) | |
tree | 17d179e83fbdb413aefe69c953ef84b0ffa7a848 /net | |
parent | da9eb43b9a5626de7c39edeb8374a3363493de20 (diff) | |
download | linux-85aecdef77f9c5b5c0d8988db6681960f0d46ab3.tar.xz |
nfc: replace improper check device_is_registered() in netlink related functions
commit da5c0f119203ad9728920456a0f52a6d850c01cd upstream.
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: 3e256b8f8dfa ("NFC: add nfc subsystem core")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-rw-r--r-- | net/nfc/core.c | 29 |
1 files changed, 14 insertions, 15 deletions
diff --git a/net/nfc/core.c b/net/nfc/core.c index e752692d3680..63701a980ee1 100644 --- a/net/nfc/core.c +++ b/net/nfc/core.c @@ -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; } @@ -206,7 +206,7 @@ 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; } @@ -245,7 +245,7 @@ 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; } @@ -290,7 +290,7 @@ 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; } @@ -334,7 +334,7 @@ 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; } @@ -400,7 +400,7 @@ 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; } @@ -446,7 +446,7 @@ 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; } @@ -493,7 +493,7 @@ 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; @@ -550,7 +550,7 @@ 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; } @@ -599,7 +599,7 @@ 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; } @@ -1127,6 +1127,7 @@ 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); @@ -1159,12 +1160,10 @@ 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); } |