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Kuniyuki Iwashima 47f6090bcf Bluetooth: Fix use-after-free in l2cap_sock_cleanup_listen() 
[ Upstream commit 862c628108 ]

syzbot reported the splat below without a repro.

In the splat, a single thread calling bt_accept_dequeue() freed sk
and touched it after that.

The root cause would be the racy l2cap_sock_cleanup_listen() call
added by the cited commit.

bt_accept_dequeue() is called under lock_sock() except for
l2cap_sock_release().

Two threads could see the same socket during the list iteration
in bt_accept_dequeue():

  CPU1                        CPU2 (close())
  ----                        ----
  sock_hold(sk)               sock_hold(sk);
  lock_sock(sk)   <-- block close()
  sock_put(sk)
  bt_accept_unlink(sk)
    sock_put(sk)  <-- refcnt by bt_accept_enqueue()
  release_sock(sk)
                              lock_sock(sk)
                              sock_put(sk)
                              bt_accept_unlink(sk)
                                sock_put(sk)        <-- last refcnt
                              bt_accept_unlink(sk)  <-- UAF

Depending on the timing, the other thread could show up in the
"Freed by task" part.

Let's call l2cap_sock_cleanup_listen() under lock_sock() in
l2cap_sock_release().

[0]:
BUG: KASAN: slab-use-after-free in debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline]
BUG: KASAN: slab-use-after-free in do_raw_spin_lock+0x26f/0x2b0 kernel/locking/spinlock_debug.c:115
Read of size 4 at addr ffff88803b7eb1c4 by task syz.5.3276/16995
CPU: 3 UID: 0 PID: 16995 Comm: syz.5.3276 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline]
 do_raw_spin_lock+0x26f/0x2b0 kernel/locking/spinlock_debug.c:115
 spin_lock_bh include/linux/spinlock.h:356 [inline]
 release_sock+0x21/0x220 net/core/sock.c:3746
 bt_accept_dequeue+0x505/0x600 net/bluetooth/af_bluetooth.c:312
 l2cap_sock_cleanup_listen+0x5c/0x2a0 net/bluetooth/l2cap_sock.c:1451
 l2cap_sock_release+0x5c/0x210 net/bluetooth/l2cap_sock.c:1425
 __sock_release+0xb3/0x270 net/socket.c:649
 sock_close+0x1c/0x30 net/socket.c:1439
 __fput+0x3ff/0xb70 fs/file_table.c:468
 task_work_run+0x14d/0x240 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2accf8ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdb6cb1378 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00000000000426fb RCX: 00007f2accf8ebe9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f2acd1b7da0 R08: 0000000000000001 R09: 00000012b6cb166f
R10: 0000001b30e20000 R11: 0000000000000246 R12: 00007f2acd1b609c
R13: 00007f2acd1b6090 R14: ffffffffffffffff R15: 00007ffdb6cb1490
 </TASK>

Allocated by task 5326:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:405
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4365 [inline]
 __kmalloc_noprof+0x223/0x510 mm/slub.c:4377
 kmalloc_noprof include/linux/slab.h:909 [inline]
 sk_prot_alloc+0x1a8/0x2a0 net/core/sock.c:2239
 sk_alloc+0x36/0xc20 net/core/sock.c:2295
 bt_sock_alloc+0x3b/0x3a0 net/bluetooth/af_bluetooth.c:151
 l2cap_sock_alloc.constprop.0+0x33/0x1d0 net/bluetooth/l2cap_sock.c:1894
 l2cap_sock_new_connection_cb+0x101/0x240 net/bluetooth/l2cap_sock.c:1482
 l2cap_connect_cfm+0x4c4/0xf80 net/bluetooth/l2cap_core.c:7287
 hci_connect_cfm include/net/bluetooth/hci_core.h:2050 [inline]
 hci_remote_features_evt+0x4dd/0x970 net/bluetooth/hci_event.c:3712
 hci_event_func net/bluetooth/hci_event.c:7519 [inline]
 hci_event_packet+0xa0d/0x11c0 net/bluetooth/hci_event.c:7573
 hci_rx_work+0x2c5/0x16b0 net/bluetooth/hci_core.c:4071
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 16995:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:243 [inline]
 __kasan_slab_free+0x60/0x70 mm/kasan/common.c:275
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2417 [inline]
 slab_free mm/slub.c:4680 [inline]
 kfree+0x2b4/0x4d0 mm/slub.c:4879
 sk_prot_free net/core/sock.c:2278 [inline]
 __sk_destruct+0x75f/0x9a0 net/core/sock.c:2373
 sk_destruct+0xc2/0xf0 net/core/sock.c:2401
 __sk_free+0xf4/0x3e0 net/core/sock.c:2412
 sk_free+0x6a/0x90 net/core/sock.c:2423
 sock_put include/net/sock.h:1960 [inline]
 bt_accept_unlink+0x245/0x2e0 net/bluetooth/af_bluetooth.c:262
 bt_accept_dequeue+0x517/0x600 net/bluetooth/af_bluetooth.c:308
 l2cap_sock_cleanup_listen+0x5c/0x2a0 net/bluetooth/l2cap_sock.c:1451
 l2cap_sock_release+0x5c/0x210 net/bluetooth/l2cap_sock.c:1425
 __sock_release+0xb3/0x270 net/socket.c:649
 sock_close+0x1c/0x30 net/socket.c:1439
 __fput+0x3ff/0xb70 fs/file_table.c:468
 task_work_run+0x14d/0x240 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Fixes: 1728137b33 ("Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_ready_cb")
Reported-by: syzbot+e5e64cdf8e92046dd3e1@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-bluetooth/68af6b9d.a70a0220.3cafd4.0032.GAE@google.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-09-09 18:50:18 +02:00
..
6lowpan 6lowpan: iphc: Fix an off-by-one check of array index 2021-07-22 16:19:03 +02:00
9p 9p/xen: fix release of IRQ 2024-12-14 19:51:21 +01:00
802 net: 802: LLC+SNAP OID:PID lookup on start of skb data 2025-01-23 17:15:49 +01:00
8021q net: vlan: fix VLAN 0 refcount imbalance of toggling filtering during runtime 2025-08-28 16:24:02 +02:00
appletalk net: appletalk: Fix use-after-free in AARP proxy probe 2025-08-28 16:24:04 +02:00
atm atm: atmtcp: Prevent arbitrary write in atmtcp_recv_control(). 2025-09-04 14:28:45 +02:00
ax25 net: ax25: Fix deadlock caused by skb_recv_datagram in ax25_recvmsg 2022-06-22 14:22:01 +02:00
batman-adv batman-adv: Ignore own maximum aggregation size during RX 2025-04-10 14:31:55 +02:00
bluetooth Bluetooth: Fix use-after-free in l2cap_sock_cleanup_listen() 2025-09-09 18:50:18 +02:00
bpf bpf: Set run context for rawtp test_run callback 2024-07-05 09:14:06 +02:00
bpfilter bpfilter: Specify the log level for the kmsg message 2021-06-25 13:13:50 +02:00
bridge netfilter: br_netfilter: do not check confirmed bit in br_nf_local_in() after confirm 2025-09-09 18:50:18 +02:00
caif caif: reduce stack size, again 2025-08-28 16:24:07 +02:00
can can: bcm: add missing rcu read protection for procfs content 2025-06-04 14:38:06 +02:00
ceph libceph: fix race between delayed_work() and ceph_monc_stop() 2024-07-18 13:07:42 +02:00
core netpoll: prevent hanging NAPI when netcons gets enabled 2025-08-28 16:24:13 +02:00
dcb net: dcb: choose correct policy to parse DCB_ATTR_BCN 2023-08-11 15:13:53 +02:00
dccp net: fix data-races around sk->sk_forward_alloc 2025-01-23 17:16:04 +01:00
dns_resolver keys, dns: Fix size check of V1 server-list header 2024-01-25 14:52:46 -08:00
dsa net: dsa: tag_brcm: legacy: fix pskb_may_pull length 2025-06-27 11:05:17 +01:00
ethernet gro: remove rcu_read_lock/rcu_read_unlock from gro_complete handlers 2024-09-12 11:07:47 +02:00
ethtool net: ethtool: Don't call .cleanup_data when prepare_data fails 2025-05-02 07:43:52 +02:00
hsr net, hsr: reject HSR frame if skb can't hold tag 2025-08-28 16:24:30 +02:00
ieee802154 net: ieee802154: do not leave a dangling sk pointer in ieee802154_create() 2024-12-14 19:51:37 +01:00
ife net: sched: ife: fix potential use-after-free 2024-01-05 15:13:29 +01:00
ipv4 net: ipv4: fix regression in local-broadcast routes 2025-09-04 14:28:45 +02:00
ipv6 netfilter: nf_reject: don't leak dst refcount for loopback packets 2025-08-28 16:24:39 +02:00
iucv s390/iucv: fix receive buffer virtual vs physical address confusion 2024-09-04 13:23:27 +02:00
kcm kcm: Serialise kcm_sendmsg() for the same socket. 2024-09-04 13:23:32 +02:00
key net: af_key: fix sadb_x_filter validation 2023-08-26 14:23:32 +02:00
l2tp genetlink: hold RCU in genlmsg_mcast() 2024-11-01 01:52:34 +01:00
l3mdev net: Add l3mdev index to flow struct and avoid oif reset for port devices 2024-10-17 15:11:57 +02:00
lapb net: lapb: Use list_for_each_entry() to simplify code in lapb_iface.c 2021-06-08 16:31:25 -07:00
llc llc: fix data loss when reading from a socket in llc_ui_recvmsg() 2025-06-04 14:38:06 +02:00
mac80211 wifi: mac80211: check basic rates validity in sta_link_apply_parameters 2025-08-28 16:24:39 +02:00
mac802154 mac802154: check local interfaces before deleting sdata list 2025-01-23 17:16:00 +01:00
mctp net: mctp: Prevent duplicate binds 2025-08-28 16:24:20 +02:00
mpls mpls: Use rcu_dereference_rtnl() in mpls_route_input_rcu(). 2025-06-27 11:05:36 +01:00
mptcp mptcp: disable add_addr retransmission when timeout is 0 2025-08-28 16:24:35 +02:00
ncsi net: ncsi: Fix buffer overflow in fetching version id 2025-08-28 16:24:22 +02:00
netfilter netfilter: conntrack: helper: Replace -EEXIST by -EBUSY 2025-09-09 18:50:18 +02:00
netlabel calipso: unlock rcu before returning -EAFNOSUPPORT 2025-06-27 11:05:22 +01:00
netlink netlink: avoid infinite retry looping in netlink_unicast() 2025-08-28 16:24:15 +02:00
netrom netrom: check buffer length before accessing it 2025-01-09 13:28:46 +01:00
nfc NFC: nci: uart: Set tty->disc_data only in success path 2025-06-27 11:05:25 +01:00
nsh nsh: Restore skb->{protocol,data,mac_header} for outer header in nsh_gso_segment(). 2024-05-17 11:50:48 +02:00
openvswitch net: openvswitch: Fix the dead loop of MPLS parse 2025-06-27 11:05:14 +01:00
packet net/packet: fix a race in packet_set_ring() and packet_notifier() 2025-08-28 16:24:14 +02:00
phonet phonet/pep: Move call to pn_skb_get_dst_sockaddr() earlier in pep_sock_accept() 2025-08-28 16:23:59 +02:00
psample psample: Require 'CAP_NET_ADMIN' when joining "packets" group 2023-12-13 18:36:37 +01:00
qrtr net: qrtr: Update packets cloning when broadcasting 2024-10-17 15:11:08 +02:00
rds net:rds: Fix possible deadlock in rds_message_put 2024-09-04 13:23:39 +02:00
rfkill net: rfkill: gpio: Add check for clk_enable() 2024-12-14 19:50:58 +01:00
rose rose: fix dangling neighbour pointers in rose_rt_device_down() 2025-07-10 15:57:46 +02:00
rxrpc rxrpc: Fix oops due to non-existence of prealloc backlog struct 2025-07-17 18:30:48 +02:00
sched net/sched: Remove unnecessary WARNING condition for empty child qdisc in htb_activate 2025-08-28 16:24:38 +02:00
sctp sctp: initialize more fields in sctp_v6_from_sk() 2025-09-04 14:28:46 +02:00
smc net/smc: fix data error when recvmsg with MSG_PEEK flag 2025-03-13 12:49:57 +01:00
strparser bpf: sockmap, strparser, and tls are reusing qdisc_skb_cb and colliding 2021-11-18 19:17:11 +01:00
sunrpc sunrpc: fix race in cache cleanup causing stale nextcheck time 2025-06-27 11:05:29 +01:00
switchdev net: make switchdev_bridge_port_{,unoffload} loosely coupled with the bridge 2021-08-04 12:35:07 +01:00
tipc tipc: Fix use-after-free in tipc_conn_close(). 2025-07-17 18:30:46 +02:00
tls bpf, ktls: Fix data corruption when using bpf_msg_pop_data() in ktls 2025-08-28 16:24:07 +02:00
unix af_unix: Don't set -ECONNRESET for consumed OOB skb. 2025-07-10 15:57:38 +02:00
vmw_vsock vsock: Do not allow binding to VMADDR_PORT_ANY 2025-08-28 16:24:14 +02:00
wireless wifi: cfg80211: fix use-after-free in cmp_bss() 2025-09-09 18:50:18 +02:00
x25 net/x25: fix incorrect parameter validation in the x25_getsockopt() function 2024-03-26 18:21:23 -04:00
xdp xsk: fix OOB map writes when deleting elements 2024-12-14 19:51:33 +01:00
xfrm xfrm: Sanitize marks before insert 2025-06-04 14:38:05 +02:00
compat.c net: Return the correct errno code 2021-06-03 15:13:56 -07:00
devres.c net: devres: Correct a grammatical error 2021-06-11 12:55:28 -07:00
Kconfig Remove DECnet support from kernel 2023-06-21 15:59:15 +02:00
Makefile Remove DECnet support from kernel 2023-06-21 15:59:15 +02:00
socket.c net: explicitly clear the sk pointer, when pf->create fails 2024-10-17 15:12:00 +02:00
sysctl_net.c net: Ensure net namespace isolation of sysctls 2021-04-12 13:27:11 -07:00