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Filename Latest commit message Latest commit date
Kuniyuki Iwashima e359b742ea tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request().
[ Upstream commit 2e7cbbbe3d61c63606994b7ff73c72537afe2e1c ]

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: 45c8a6cc2bcd ("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>
2025-10-29 13:59:51 +01:00
arch sparc: fix accurate exception reporting in copy_{from,to}_user for M7 2025-10-29 13:59:49 +01:00
block block: use int to store blk_stack_limits() return value 2025-10-29 13:59:46 +01:00
certs
crypto
Documentation Documentation: ACPI: Fix parent device references 2025-08-28 16:21:23 +02:00
drivers drm/vmwgfx: Fix Use-after-free in validation 2025-10-29 13:59:51 +01:00
fs Squashfs: fix uninit-value in squashfs_get_parent 2025-10-29 13:59:50 +01:00
include scsi: libsas: Add sas_task_find_rq() 2025-10-29 13:59:51 +01:00
init bpfilter: match bit size of bpfilter_umh to that of the kernel 2025-07-17 18:24:51 +02:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:02:52 +01:00
kernel cgroup: split cgroup_destroy_wq into 3 workqueues 2025-10-02 13:34:30 +02:00
lib lib: test_objagg: Set error message in check_expect_hints_stats() 2025-07-17 18:24:56 +02:00
LICENSES
mm mm: hugetlb: avoid soft lockup when mprotect to large memory area 2025-10-29 13:59:50 +01:00
net tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request(). 2025-10-29 13:59:51 +01:00
samples samples: mei: Fix building on musl libc 2025-08-28 16:21:19 +02:00
scripts randstruct: gcc-plugin: Fix attribute addition 2025-09-09 18:44:01 +02:00
security securityfs: don't pin dentries twice, once is enough... 2025-08-28 16:21:24 +02:00
sound ASoC: Intel: bytcr_rt5651: Fix invalid quirk input mapping 2025-10-29 13:59:48 +01:00
tools perf session: Fix handling when buffer exceeds 2 GiB 2025-10-29 13:59:50 +01:00
usr kbuild: hdrcheck: fix cross build with clang 2025-07-17 18:24:51 +02:00
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS platform: Add Surface platform directory 2025-06-27 11:02:56 +01:00
Makefile Linux 5.4.300 2025-10-02 13:34:35 +02:00
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Linux kernel
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