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Message-Id: <20230622150331.1242706-1-linma@zju.edu.cn>
Date: Thu, 22 Jun 2023 23:03:31 +0800
From: Lin Ma <linma@....edu.cn>
To: krzysztof.kozlowski@...aro.org,
	avem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	netdev@...r.kernel.org
Cc: Lin Ma <linma@....edu.cn>
Subject: [PATCH v2] net: nfc: Fix use-after-free caused by nfc_llcp_find_local

This commit fixes several use-after-free that caused by function
nfc_llcp_find_local(). For example, one UAF can happen when below buggy
time window occurs.

// nfc_genl_llc_get_params   | // nfc_unregister_device
                             |
dev = nfc_get_device(idx);   | device_lock(...)
if (!dev)                    | dev->shutting_down = true;
    return -ENODEV;          | device_unlock(...);
                             |
device_lock(...);            |   // nfc_llcp_unregister_device
                             |   nfc_llcp_find_local()
nfc_llcp_find_local(...);    |
                             |   local_cleanup()
if (!local) {                |
    rc = -ENODEV;            |     // nfc_llcp_local_put
    goto exit;               |     kref_put(.., local_release)
}                            |
                             |       // local_release
                             |       list_del(&local->list)
  // nfc_genl_send_params    |       kfree()
  local->dev->idx !!!UAF!!!  |
                             |

and the crash trace for the one of the discussed UAF like:

BUG: KASAN: slab-use-after-free in nfc_genl_llc_get_params+0x72f/0x780  net/nfc/netlink.c:1045
Read of size 8 at addr ffff888105b0e410 by task 20114

Call Trace:
 <TASK>
 __dump_stack  lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x72/0xa0  lib/dump_stack.c:106
 print_address_description  mm/kasan/report.c:319 [inline]
 print_report+0xcc/0x620  mm/kasan/report.c:430
 kasan_report+0xb2/0xe0  mm/kasan/report.c:536
 nfc_genl_send_params  net/nfc/netlink.c:999 [inline]
 nfc_genl_llc_get_params+0x72f/0x780  net/nfc/netlink.c:1045
 genl_family_rcv_msg_doit.isra.0+0x1ee/0x2e0  net/netlink/genetlink.c:968
 genl_family_rcv_msg  net/netlink/genetlink.c:1048 [inline]
 genl_rcv_msg+0x503/0x7d0  net/netlink/genetlink.c:1065
 netlink_rcv_skb+0x161/0x430  net/netlink/af_netlink.c:2548
 genl_rcv+0x28/0x40  net/netlink/genetlink.c:1076
 netlink_unicast_kernel  net/netlink/af_netlink.c:1339 [inline]
 netlink_unicast+0x644/0x900  net/netlink/af_netlink.c:1365
 netlink_sendmsg+0x934/0xe70  net/netlink/af_netlink.c:1913
 sock_sendmsg_nosec  net/socket.c:724 [inline]
 sock_sendmsg+0x1b6/0x200  net/socket.c:747
 ____sys_sendmsg+0x6e9/0x890  net/socket.c:2501
 ___sys_sendmsg+0x110/0x1b0  net/socket.c:2555
 __sys_sendmsg+0xf7/0x1d0  net/socket.c:2584
 do_syscall_x64  arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3f/0x90  arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7f34640a2389
RSP: 002b:00007f3463415168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f34641c1f80 RCX: 00007f34640a2389
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000006
RBP: 00007f34640ed493 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe38449ecf R14: 00007f3463415300 R15: 0000000000022000
 </TASK>

Allocated by task 20116:
 kasan_save_stack+0x22/0x50  mm/kasan/common.c:45
 kasan_set_track+0x25/0x30  mm/kasan/common.c:52
 ____kasan_kmalloc  mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x7f/0x90  mm/kasan/common.c:383
 kmalloc  include/linux/slab.h:580 [inline]
 kzalloc  include/linux/slab.h:720 [inline]
 nfc_llcp_register_device+0x49/0xa40  net/nfc/llcp_core.c:1567
 nfc_register_device+0x61/0x260  net/nfc/core.c:1124
 nci_register_device+0x776/0xb20  net/nfc/nci/core.c:1257
 virtual_ncidev_open+0x147/0x230  drivers/nfc/virtual_ncidev.c:148
 misc_open+0x379/0x4a0  drivers/char/misc.c:165
 chrdev_open+0x26c/0x780  fs/char_dev.c:414
 do_dentry_open+0x6c4/0x12a0  fs/open.c:920
 do_open  fs/namei.c:3560 [inline]
 path_openat+0x24fe/0x37e0  fs/namei.c:3715
 do_filp_open+0x1ba/0x410  fs/namei.c:3742
 do_sys_openat2+0x171/0x4c0  fs/open.c:1356
 do_sys_open  fs/open.c:1372 [inline]
 __do_sys_openat  fs/open.c:1388 [inline]
 __se_sys_openat  fs/open.c:1383 [inline]
 __x64_sys_openat+0x143/0x200  fs/open.c:1383
 do_syscall_x64  arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3f/0x90  arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x72/0xdc

Freed by task 20115:
 kasan_save_stack+0x22/0x50  mm/kasan/common.c:45
 kasan_set_track+0x25/0x30  mm/kasan/common.c:52
 kasan_save_free_info+0x2e/0x50  mm/kasan/generic.c:521
 ____kasan_slab_free  mm/kasan/common.c:236 [inline]
 ____kasan_slab_free  mm/kasan/common.c:200 [inline]
 __kasan_slab_free+0x10a/0x190  mm/kasan/common.c:244
 kasan_slab_free  include/linux/kasan.h:162 [inline]
 slab_free_hook  mm/slub.c:1781 [inline]
 slab_free_freelist_hook  mm/slub.c:1807 [inline]
 slab_free  mm/slub.c:3787 [inline]
 __kmem_cache_free+0x7a/0x190  mm/slub.c:3800
 local_release  net/nfc/llcp_core.c:174 [inline]
 kref_put  include/linux/kref.h:65 [inline]
 nfc_llcp_local_put  net/nfc/llcp_core.c:182 [inline]
 nfc_llcp_local_put  net/nfc/llcp_core.c:177 [inline]
 nfc_llcp_unregister_device+0x206/0x290  net/nfc/llcp_core.c:1620
 nfc_unregister_device+0x160/0x1d0  net/nfc/core.c:1179
 virtual_ncidev_close+0x52/0xa0  drivers/nfc/virtual_ncidev.c:163
 __fput+0x252/0xa20  fs/file_table.c:321
 task_work_run+0x174/0x270  kernel/task_work.c:179
 resume_user_mode_work  include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop  kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x108/0x110  kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work  kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x21/0x50  kernel/entry/common.c:297
 do_syscall_64+0x4c/0x90  arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x72/0xdc

Last potentially related work creation:
 kasan_save_stack+0x22/0x50  mm/kasan/common.c:45
 __kasan_record_aux_stack+0x95/0xb0  mm/kasan/generic.c:491
 kvfree_call_rcu+0x29/0xa80  kernel/rcu/tree.c:3328
 drop_sysctl_table+0x3be/0x4e0  fs/proc/proc_sysctl.c:1735
 unregister_sysctl_table.part.0+0x9c/0x190  fs/proc/proc_sysctl.c:1773
 unregister_sysctl_table+0x24/0x30  fs/proc/proc_sysctl.c:1753
 neigh_sysctl_unregister+0x5f/0x80  net/core/neighbour.c:3895
 addrconf_notify+0x140/0x17b0  net/ipv6/addrconf.c:3684
 notifier_call_chain+0xbe/0x210  kernel/notifier.c:87
 call_netdevice_notifiers_info+0xb5/0x150  net/core/dev.c:1937
 call_netdevice_notifiers_extack  net/core/dev.c:1975 [inline]
 call_netdevice_notifiers  net/core/dev.c:1989 [inline]
 dev_change_name+0x3c3/0x870  net/core/dev.c:1211
 dev_ifsioc+0x800/0xf70  net/core/dev_ioctl.c:376
 dev_ioctl+0x3d9/0xf80  net/core/dev_ioctl.c:542
 sock_do_ioctl+0x160/0x260  net/socket.c:1213
 sock_ioctl+0x3f9/0x670  net/socket.c:1316
 vfs_ioctl  fs/ioctl.c:51 [inline]
 __do_sys_ioctl  fs/ioctl.c:870 [inline]
 __se_sys_ioctl  fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x19e/0x210  fs/ioctl.c:856
 do_syscall_x64  arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3f/0x90  arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x72/0xdc

The buggy address belongs to the object at ffff888105b0e400
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 16 bytes inside of
 freed 1024-byte region [ffff888105b0e400, ffff888105b0e800)

The buggy address belongs to the physical page:
page:ffffea000416c200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x105b08
head:ffffea000416c200 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x200000000010200(slab|head|node=0|zone=2)
raw: 0200000000010200 ffff8881000430c0 ffffea00044c7010 ffffea0004510e10
raw: 0000000000000000 00000000000a000a 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888105b0e300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888105b0e380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888105b0e400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888105b0e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888105b0e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

It seems that the root cause of such use-after-free is the current
implementation of nfc_llcp_find_local() suffers from the race condition.
For example, the llcp_sock_bind() gets the reference like below

// llcp_sock_bind()

    local = nfc_llcp_find_local(dev); // A
    ..... \
           | raceable
    ..... /
    llcp_sock->local = nfc_llcp_local_get(local); // B

There is a apparent race window that one can possibly drop the reference
and free the local object fetched in (A) before (B) gets the reference.

To avoid such cases, this patch re-implements the nfc_llcp_find_local()
to make sure it grabs the reference under the lock protection. We also
add other reference cleanup code for error handling. Hence, the
reference promises that even when the nfc_llcp_unregister_device() is
called, no caller of nfc_llcp_find_local() will get alike UAF.

Fixes: 52feb444a903 ("NFC: Extend netlink interface for LTO, RW, and MIUX parameters support")
Fixes: c7aa12252f51 ("NFC: Take a reference on the LLCP local pointer
when creating a socket")
Signed-off-by: Lin Ma <linma@....edu.cn>
---
V1 -> V2: not just fix nfc_genl_llc_{{get/set}_params/sdreq}
          but concern on all callers of nfc_llcp_find_local()

 net/nfc/llcp.h          |  1 -
 net/nfc/llcp_commands.c | 12 ++++++++---
 net/nfc/llcp_core.c     | 47 +++++++++++++++++++++++++++++++++++------
 net/nfc/llcp_sock.c     | 16 +++++++-------
 net/nfc/netlink.c       | 20 +++++++++++++-----
 net/nfc/nfc.h           |  1 +
 6 files changed, 74 insertions(+), 23 deletions(-)

diff --git a/net/nfc/llcp.h b/net/nfc/llcp.h
index c1d9be636933..d8345ed57c95 100644
--- a/net/nfc/llcp.h
+++ b/net/nfc/llcp.h
@@ -201,7 +201,6 @@ void nfc_llcp_sock_link(struct llcp_sock_list *l, struct sock *s);
 void nfc_llcp_sock_unlink(struct llcp_sock_list *l, struct sock *s);
 void nfc_llcp_socket_remote_param_init(struct nfc_llcp_sock *sock);
 struct nfc_llcp_local *nfc_llcp_find_local(struct nfc_dev *dev);
-struct nfc_llcp_local *nfc_llcp_local_get(struct nfc_llcp_local *local);
 int nfc_llcp_local_put(struct nfc_llcp_local *local);
 u8 nfc_llcp_get_sdp_ssap(struct nfc_llcp_local *local,
 			 struct nfc_llcp_sock *sock);
diff --git a/net/nfc/llcp_commands.c b/net/nfc/llcp_commands.c
index 41e3a20c8935..5d2d4bc26ef9 100644
--- a/net/nfc/llcp_commands.c
+++ b/net/nfc/llcp_commands.c
@@ -359,6 +359,7 @@ int nfc_llcp_send_symm(struct nfc_dev *dev)
 	struct sk_buff *skb;
 	struct nfc_llcp_local *local;
 	u16 size = 0;
+	int err;
 
 	local = nfc_llcp_find_local(dev);
 	if (local == NULL)
@@ -368,8 +369,10 @@ int nfc_llcp_send_symm(struct nfc_dev *dev)
 	size += dev->tx_headroom + dev->tx_tailroom + NFC_HEADER_SIZE;
 
 	skb = alloc_skb(size, GFP_KERNEL);
-	if (skb == NULL)
-		return -ENOMEM;
+	if (skb == NULL) {
+		err = -ENOMEM;
+		goto out;
+	}
 
 	skb_reserve(skb, dev->tx_headroom + NFC_HEADER_SIZE);
 
@@ -379,8 +382,11 @@ int nfc_llcp_send_symm(struct nfc_dev *dev)
 
 	nfc_llcp_send_to_raw_sock(local, skb, NFC_DIRECTION_TX);
 
-	return nfc_data_exchange(dev, local->target_idx, skb,
+	err = nfc_data_exchange(dev, local->target_idx, skb,
 				 nfc_llcp_recv, local);
+out:
+	nfc_llcp_local_put(local);
+	return err;
 }
 
 int nfc_llcp_send_connect(struct nfc_llcp_sock *sock)
diff --git a/net/nfc/llcp_core.c b/net/nfc/llcp_core.c
index a27e1842b2a0..34eea997318c 100644
--- a/net/nfc/llcp_core.c
+++ b/net/nfc/llcp_core.c
@@ -17,6 +17,8 @@
 static u8 llcp_magic[3] = {0x46, 0x66, 0x6d};
 
 static LIST_HEAD(llcp_devices);
+/* Protects llcp_devices list */
+static DEFINE_SPINLOCK(llcp_devices_lock);
 
 static void nfc_llcp_rx_skb(struct nfc_llcp_local *local, struct sk_buff *skb);
 
@@ -169,7 +171,6 @@ static void local_release(struct kref *ref)
 
 	local = container_of(ref, struct nfc_llcp_local, ref);
 
-	list_del(&local->list);
 	local_cleanup(local);
 	kfree(local);
 }
@@ -282,12 +283,33 @@ static void nfc_llcp_sdreq_timer(struct timer_list *t)
 struct nfc_llcp_local *nfc_llcp_find_local(struct nfc_dev *dev)
 {
 	struct nfc_llcp_local *local;
+	struct nfc_llcp_local *res = NULL;
 
+	spin_lock(&llcp_devices_lock);
 	list_for_each_entry(local, &llcp_devices, list)
-		if (local->dev == dev)
+		if (local->dev == dev) {
+			res = nfc_llcp_local_get(local);
+			break;
+		}
+	spin_unlock(&llcp_devices_lock);
+
+	return res;
+}
+
+struct nfc_llcp_local *nfc_llcp_remove_local(struct nfc_dev *dev)
+{
+	struct nfc_llcp_local *local, *tmp;
+
+	spin_lock(&llcp_devices_lock);
+	list_for_each_entry_safe(local, tmp, &llcp_devices, list)
+		if (local->dev == dev) {
+			list_del(&local->list);
+			spin_unlock(&llcp_devices_lock);
 			return local;
+		}
+	spin_unlock(&llcp_devices_lock);
 
-	pr_debug("No device found\n");
+	pr_warn("Shutting down device not found\n");
 
 	return NULL;
 }
@@ -608,12 +630,15 @@ u8 *nfc_llcp_general_bytes(struct nfc_dev *dev, size_t *general_bytes_len)
 
 	*general_bytes_len = local->gb_len;
 
+	nfc_llcp_local_put(local);
+
 	return local->gb;
 }
 
 int nfc_llcp_set_remote_gb(struct nfc_dev *dev, const u8 *gb, u8 gb_len)
 {
 	struct nfc_llcp_local *local;
+	int err;
 
 	if (gb_len < 3 || gb_len > NFC_MAX_GT_LEN)
 		return -EINVAL;
@@ -630,12 +655,16 @@ int nfc_llcp_set_remote_gb(struct nfc_dev *dev, const u8 *gb, u8 gb_len)
 
 	if (memcmp(local->remote_gb, llcp_magic, 3)) {
 		pr_err("MAC does not support LLCP\n");
-		return -EINVAL;
+		err = -EINVAL;
+		goto out;
 	}
 
-	return nfc_llcp_parse_gb_tlv(local,
+	err = nfc_llcp_parse_gb_tlv(local,
 				     &local->remote_gb[3],
 				     local->remote_gb_len - 3);
+out:
+	nfc_llcp_local_put(local);
+	return err;
 }
 
 static u8 nfc_llcp_dsap(const struct sk_buff *pdu)
@@ -1517,6 +1546,8 @@ int nfc_llcp_data_received(struct nfc_dev *dev, struct sk_buff *skb)
 
 	__nfc_llcp_recv(local, skb);
 
+	nfc_llcp_local_put(local);
+
 	return 0;
 }
 
@@ -1533,6 +1564,8 @@ void nfc_llcp_mac_is_down(struct nfc_dev *dev)
 
 	/* Close and purge all existing sockets */
 	nfc_llcp_socket_release(local, true, 0);
+
+	nfc_llcp_local_put(local);
 }
 
 void nfc_llcp_mac_is_up(struct nfc_dev *dev, u32 target_idx,
@@ -1558,6 +1591,8 @@ void nfc_llcp_mac_is_up(struct nfc_dev *dev, u32 target_idx,
 		mod_timer(&local->link_timer,
 			  jiffies + msecs_to_jiffies(local->remote_lto));
 	}
+
+	nfc_llcp_local_put(local);
 }
 
 int nfc_llcp_register_device(struct nfc_dev *ndev)
@@ -1608,7 +1643,7 @@ int nfc_llcp_register_device(struct nfc_dev *ndev)
 
 void nfc_llcp_unregister_device(struct nfc_dev *dev)
 {
-	struct nfc_llcp_local *local = nfc_llcp_find_local(dev);
+	struct nfc_llcp_local *local = nfc_llcp_remove_local(dev);
 
 	if (local == NULL) {
 		pr_debug("No such device\n");
diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index 77642d18a3b4..fa6a9e455b53 100644
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -99,7 +99,7 @@ static int llcp_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
 	}
 
 	llcp_sock->dev = dev;
-	llcp_sock->local = nfc_llcp_local_get(local);
+	llcp_sock->local = local;
 	llcp_sock->nfc_protocol = llcp_addr.nfc_protocol;
 	llcp_sock->service_name_len = min_t(unsigned int,
 					    llcp_addr.service_name_len,
@@ -186,7 +186,7 @@ static int llcp_raw_sock_bind(struct socket *sock, struct sockaddr *addr,
 	}
 
 	llcp_sock->dev = dev;
-	llcp_sock->local = nfc_llcp_local_get(local);
+	llcp_sock->local = local;
 	llcp_sock->nfc_protocol = llcp_addr.nfc_protocol;
 
 	nfc_llcp_sock_link(&local->raw_sockets, sk);
@@ -696,20 +696,22 @@ static int llcp_sock_connect(struct socket *sock, struct sockaddr *_addr,
 	if (dev->dep_link_up == false) {
 		ret = -ENOLINK;
 		device_unlock(&dev->dev);
-		goto put_dev;
+		goto sock_llcp_put_local;
 	}
 	device_unlock(&dev->dev);
 
 	if (local->rf_mode == NFC_RF_INITIATOR &&
 	    addr->target_idx != local->target_idx) {
 		ret = -ENOLINK;
-		goto put_dev;
+		goto sock_llcp_put_local;
 	}
 
 	llcp_sock->dev = dev;
-	llcp_sock->local = nfc_llcp_local_get(local);
+	llcp_sock->local = local;
 	llcp_sock->ssap = nfc_llcp_get_local_ssap(local);
 	if (llcp_sock->ssap == LLCP_SAP_MAX) {
+		llcp_sock->local = NULL;
+		llcp_sock->dev = NULL;
 		ret = -ENOMEM;
 		goto sock_llcp_put_local;
 	}
@@ -758,9 +760,7 @@ static int llcp_sock_connect(struct socket *sock, struct sockaddr *_addr,
 	nfc_llcp_put_ssap(local, llcp_sock->ssap);
 
 sock_llcp_put_local:
-	nfc_llcp_local_put(llcp_sock->local);
-	llcp_sock->local = NULL;
-	llcp_sock->dev = NULL;
+	nfc_llcp_local_put(local);
 
 put_dev:
 	nfc_put_device(dev);
diff --git a/net/nfc/netlink.c b/net/nfc/netlink.c
index b9264e730fd9..e9ac6a6f934e 100644
--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -1039,11 +1039,14 @@ static int nfc_genl_llc_get_params(struct sk_buff *skb, struct genl_info *info)
 	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 	if (!msg) {
 		rc = -ENOMEM;
-		goto exit;
+		goto put_local;
 	}
 
 	rc = nfc_genl_send_params(msg, local, info->snd_portid, info->snd_seq);
 
+put_local:
+	nfc_llcp_local_put(local);
+
 exit:
 	device_unlock(&dev->dev);
 
@@ -1105,7 +1108,7 @@ static int nfc_genl_llc_set_params(struct sk_buff *skb, struct genl_info *info)
 	if (info->attrs[NFC_ATTR_LLC_PARAM_LTO]) {
 		if (dev->dep_link_up) {
 			rc = -EINPROGRESS;
-			goto exit;
+			goto put_local;
 		}
 
 		local->lto = nla_get_u8(info->attrs[NFC_ATTR_LLC_PARAM_LTO]);
@@ -1117,6 +1120,9 @@ static int nfc_genl_llc_set_params(struct sk_buff *skb, struct genl_info *info)
 	if (info->attrs[NFC_ATTR_LLC_PARAM_MIUX])
 		local->miux = cpu_to_be16(miux);
 
+put_local:
+	nfc_llcp_local_put(local);
+
 exit:
 	device_unlock(&dev->dev);
 
@@ -1172,7 +1178,7 @@ static int nfc_genl_llc_sdreq(struct sk_buff *skb, struct genl_info *info)
 
 		if (rc != 0) {
 			rc = -EINVAL;
-			goto exit;
+			goto put_local;
 		}
 
 		if (!sdp_attrs[NFC_SDP_ATTR_URI])
@@ -1191,7 +1197,7 @@ static int nfc_genl_llc_sdreq(struct sk_buff *skb, struct genl_info *info)
 		sdreq = nfc_llcp_build_sdreq_tlv(tid, uri, uri_len);
 		if (sdreq == NULL) {
 			rc = -ENOMEM;
-			goto exit;
+			goto put_local;
 		}
 
 		tlvs_len += sdreq->tlv_len;
@@ -1201,10 +1207,14 @@ static int nfc_genl_llc_sdreq(struct sk_buff *skb, struct genl_info *info)
 
 	if (hlist_empty(&sdreq_list)) {
 		rc = -EINVAL;
-		goto exit;
+		goto put_local;
 	}
 
 	rc = nfc_llcp_send_snl_sdreq(local, &sdreq_list, tlvs_len);
+
+put_local:
+	nfc_llcp_local_put(local);
+
 exit:
 	device_unlock(&dev->dev);
 
diff --git a/net/nfc/nfc.h b/net/nfc/nfc.h
index de2ec66d7e83..0b1e6466f4fb 100644
--- a/net/nfc/nfc.h
+++ b/net/nfc/nfc.h
@@ -52,6 +52,7 @@ int nfc_llcp_set_remote_gb(struct nfc_dev *dev, const u8 *gb, u8 gb_len);
 u8 *nfc_llcp_general_bytes(struct nfc_dev *dev, size_t *general_bytes_len);
 int nfc_llcp_data_received(struct nfc_dev *dev, struct sk_buff *skb);
 struct nfc_llcp_local *nfc_llcp_find_local(struct nfc_dev *dev);
+int nfc_llcp_local_put(struct nfc_llcp_local *local);
 int __init nfc_llcp_init(void);
 void nfc_llcp_exit(void);
 void nfc_llcp_free_sdp_tlv(struct nfc_llcp_sdp_tlv *sdp);
-- 
2.17.1


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