linux/net
Kuniyuki Iwashima eb85ad5f23 tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request().
[ Upstream commit 2e7cbbbe3d ]

syzbot reported the splat below in tcp_conn_request(). [0]

If a listener is close()d while a TFO socket is being processed in
tcp_conn_request(), inet_csk_reqsk_queue_add() does not set reqsk->sk
and calls inet_child_forget(), which calls tcp_disconnect() for the
TFO socket.

After the cited commit, tcp_disconnect() calls reqsk_fastopen_remove(),
where reqsk_put() is called due to !reqsk->sk.

Then, reqsk_fastopen_remove() in tcp_conn_request() decrements the
last req->rsk_refcnt and frees reqsk, and __reqsk_free() at the
drop_and_free label causes the refcount underflow for the listener
and double-free of the reqsk.

Let's remove reqsk_fastopen_remove() in tcp_conn_request().

Note that other callers make sure tp->fastopen_rsk is not NULL.

[0]:
refcount_t: underflow; use-after-free.
WARNING: CPU: 12 PID: 5563 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28)
Modules linked in:
CPU: 12 UID: 0 PID: 5563 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:refcount_warn_saturate (lib/refcount.c:28)
Code: ab e8 8e b4 98 ff 0f 0b c3 cc cc cc cc cc 80 3d a4 e4 d6 01 00 75 9c c6 05 9b e4 d6 01 01 48 c7 c7 e8 df fb ab e8 6a b4 98 ff <0f> 0b e9 03 5b 76 00 cc 80 3d 7d e4 d6 01 00 0f 85 74 ff ff ff c6
RSP: 0018:ffffa79fc0304a98 EFLAGS: 00010246
RAX: d83af4db1c6b3900 RBX: ffff9f65c7a69020 RCX: d83af4db1c6b3900
RDX: 0000000000000000 RSI: 00000000ffff7fff RDI: ffffffffac78a280
RBP: 000000009d781b60 R08: 0000000000007fff R09: ffffffffac6ca280
R10: 0000000000017ffd R11: 0000000000000004 R12: ffff9f65c7b4f100
R13: ffff9f65c7d23c00 R14: ffff9f65c7d26000 R15: ffff9f65c7a64ef8
FS:  00007f9f962176c0(0000) GS:ffff9f65fcf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000180 CR3: 000000000dbbe006 CR4: 0000000000372ef0
Call Trace:
 <IRQ>
 tcp_conn_request (./include/linux/refcount.h:400 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 ./include/net/sock.h:1965 ./include/net/request_sock.h:131 net/ipv4/tcp_input.c:7301)
 tcp_rcv_state_process (net/ipv4/tcp_input.c:6708)
 tcp_v6_do_rcv (net/ipv6/tcp_ipv6.c:1670)
 tcp_v6_rcv (net/ipv6/tcp_ipv6.c:1906)
 ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:438)
 ip6_input (net/ipv6/ip6_input.c:500)
 ipv6_rcv (net/ipv6/ip6_input.c:311)
 __netif_receive_skb (net/core/dev.c:6104)
 process_backlog (net/core/dev.c:6456)
 __napi_poll (net/core/dev.c:7506)
 net_rx_action (net/core/dev.c:7569 net/core/dev.c:7696)
 handle_softirqs (kernel/softirq.c:579)
 do_softirq (kernel/softirq.c:480)
 </IRQ>

Fixes: 45c8a6cc2b ("tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect().")
Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20251001233755.1340927-1-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-10-19 16:21:41 +02:00
..
6lowpan 6lowpan: iphc: Fix an off-by-one check of array index 2021-07-22 16:19:03 +02:00
9p net/9p: fix double req put in p9_fd_cancelled 2025-10-19 16:21:28 +02:00
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 net: atm: fix memory leak in atm_register_sysfs when device_register fail 2025-09-09 18:50:20 +02:00
ax25 ax25: properly unshare skbs in ax25_kiss_rcv() 2025-09-09 18:50:20 +02:00
batman-adv batman-adv: fix OOB read/write in network-coding decode 2025-09-09 18:50:21 +02:00
bluetooth Bluetooth: MGMT: Fix not exposing debug UUID on MGMT_OP_READ_EXP_FEATURES_INFO 2025-10-19 16:21:37 +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: j1939: j1939_local_ecu_get(): undo increment when j1939_local_ecu_get() fails 2025-10-02 13:39:03 +02:00
ceph libceph: fix invalid accesses to ceph_connection_v1_info 2025-10-02 13:39:01 +02:00
core bpf: Explicitly check accesses to bpf_sock_addr 2025-10-19 16:21:31 +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: microchip: linearize skb for tail-tagging switches 2025-09-09 18:50:23 +02:00
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: hsr_slave: Fix the promiscuous mode in offload mode 2025-10-02 13:39:05 +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 tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request(). 2025-10-19 16:21:41 +02:00
ipv6 icmp: fix icmp_ndo_send address translation for reply direction 2025-09-09 18:50:18 +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: fix incorrect type for ret 2025-10-02 13:39:05 +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: propagate shutdown to subflows when possible 2025-10-02 13:39:09 +02:00
ncsi net: ncsi: Fix buffer overflow in fetching version id 2025-08-28 16:24:22 +02:00
netfilter ipvs: Defer ip_vs_ftp unregister during netns cleanup 2025-10-19 16:21:36 +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 net: nfc: nci: Add parameter validation for packet data 2025-10-19 16:21:38 +02:00
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 rds: ib: Increment i_fastreg_wrs before bailing out 2025-10-02 13:39:07 +02:00
rfkill net: rfkill: gpio: Fix crash due to dereferencering uninitialized pointer 2025-10-02 13:39:09 +02:00
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 net/sctp: fix a null dereference in sctp_disposition sctp_sf_do_5_1D_ce() 2025-10-19 16:21:41 +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 minmax: add in_range() macro 2025-10-19 16:21:28 +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 leave consecutive consumed OOB skbs. 2025-10-02 13:39:14 +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