diff options
author | Lin Ma <linma@zju.edu.cn> | 2021-11-16 18:26:52 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-11-26 12:39:17 +0300 |
commit | 73a0d12114b4bc1a9def79a623264754b9df698e (patch) | |
tree | 056d53bf669b3f4a135b482481ca92e8682da4c7 /net/nfc | |
parent | cb14b196d991c864ed2d1b6e79d68a7ce38e6538 (diff) | |
download | linux-73a0d12114b4bc1a9def79a623264754b9df698e.tar.xz |
NFC: reorder the logic in nfc_{un,}register_device
[ Upstream commit 3e3b5dfcd16a3e254aab61bd1e8c417dd4503102 ]
There is a potential UAF between the unregistration routine and the NFC
netlink operations.
The race that cause that UAF can be shown as below:
(FREE) | (USE)
nfcmrvl_nci_unregister_dev | nfc_genl_dev_up
nci_close_device |
nci_unregister_device | nfc_get_device
nfc_unregister_device | nfc_dev_up
rfkill_destory |
device_del | rfkill_blocked
... | ...
The root cause for this race is concluded below:
1. The rfkill_blocked (USE) in nfc_dev_up is supposed to be placed after
the device_is_registered check.
2. Since the netlink operations are possible just after the device_add
in nfc_register_device, the nfc_dev_up() can happen anywhere during the
rfkill creation process, which leads to data race.
This patch reorder these actions to permit
1. Once device_del is finished, the nfc_dev_up cannot dereference the
rfkill object.
2. The rfkill_register need to be placed after the device_add of nfc_dev
because the parent device need to be created first. So this patch keeps
the order but inject device_lock to prevent the data race.
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Fixes: be055b2f89b5 ("NFC: RFKILL support")
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20211116152652.19217-1-linma@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/nfc')
-rw-r--r-- | net/nfc/core.c | 32 |
1 files changed, 18 insertions, 14 deletions
diff --git a/net/nfc/core.c b/net/nfc/core.c index eb377f87bcae..6800470dd6df 100644 --- a/net/nfc/core.c +++ b/net/nfc/core.c @@ -94,13 +94,13 @@ int nfc_dev_up(struct nfc_dev *dev) device_lock(&dev->dev); - if (dev->rfkill && rfkill_blocked(dev->rfkill)) { - rc = -ERFKILL; + if (!device_is_registered(&dev->dev)) { + rc = -ENODEV; goto error; } - if (!device_is_registered(&dev->dev)) { - rc = -ENODEV; + if (dev->rfkill && rfkill_blocked(dev->rfkill)) { + rc = -ERFKILL; goto error; } @@ -1117,11 +1117,7 @@ int nfc_register_device(struct nfc_dev *dev) if (rc) pr_err("Could not register llcp device\n"); - rc = nfc_genl_device_added(dev); - if (rc) - pr_debug("The userspace won't be notified that the device %s was added\n", - dev_name(&dev->dev)); - + device_lock(&dev->dev); dev->rfkill = rfkill_alloc(dev_name(&dev->dev), &dev->dev, RFKILL_TYPE_NFC, &nfc_rfkill_ops, dev); if (dev->rfkill) { @@ -1130,6 +1126,12 @@ int nfc_register_device(struct nfc_dev *dev) dev->rfkill = NULL; } } + device_unlock(&dev->dev); + + rc = nfc_genl_device_added(dev); + if (rc) + pr_debug("The userspace won't be notified that the device %s was added\n", + dev_name(&dev->dev)); return 0; } @@ -1146,10 +1148,17 @@ void nfc_unregister_device(struct nfc_dev *dev) pr_debug("dev_name=%s\n", dev_name(&dev->dev)); + rc = nfc_genl_device_removed(dev); + if (rc) + pr_debug("The userspace won't be notified that the device %s " + "was removed\n", dev_name(&dev->dev)); + + device_lock(&dev->dev); if (dev->rfkill) { rfkill_unregister(dev->rfkill); rfkill_destroy(dev->rfkill); } + device_unlock(&dev->dev); if (dev->ops->check_presence) { device_lock(&dev->dev); @@ -1159,11 +1168,6 @@ void nfc_unregister_device(struct nfc_dev *dev) cancel_work_sync(&dev->check_pres_work); } - rc = nfc_genl_device_removed(dev); - if (rc) - pr_debug("The userspace won't be notified that the device %s " - "was removed\n", dev_name(&dev->dev)); - nfc_llcp_unregister_device(dev); mutex_lock(&nfc_devlist_mutex); |