syzbot

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refcount_t: addition on 0; use-after-free.
WARNING: CPU: 0 PID: 5276 at lib/refcount.c:25 refcount_warn_saturate+0x1a8/0x20c lib/refcount.c:25
Modules linked in:
CPU: 0 PID: 5276 Comm: syz-executor.0 Not tainted 5.15.155-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : refcount_warn_saturate+0x1a8/0x20c lib/refcount.c:25
lr : refcount_warn_saturate+0x1a8/0x20c lib/refcount.c:25
sp : ffff80001d937440
x29: ffff80001d937440 x28: ffff0000e88c8848 x27: ffff0000e88c8000
x26: dfff800000000000 x25: ffff0000e475018e x24: 0000000000000000
x23: ffff700003b26ea8 x22: 0000000000000000 x21: 0000000000000002
x20: ffff0000e88c8080 x19: ffff800016d4f000 x18: 0000000000000001
x17: 0000000000000002 x16: ffff800011997230 x15: 00000000ffffffff
x14: ffff0000c7f01b40 x13: 0000000000000001 x12: 0000000000040000
x11: 0000000000002ea9 x10: ffff80001d66a000 x9 : 3bd1bc5dfe93ac00
x8 : 3bd1bc5dfe93ac00 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff80001d936bb8 x4 : ffff800014a1f7c0 x3 : ffff800008550164
x2 : 0000000000000001 x1 : 0000000100000000 x0 : 000000000000002a
Call trace:
 refcount_warn_saturate+0x1a8/0x20c lib/refcount.c:25
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 sock_hold include/net/sock.h:737 [inline]
 sk_reset_timer+0xcc/0xfc net/core/sock.c:3137
 mptcp_reset_rtx_timer net/mptcp/protocol.c:848 [inline]
 __mptcp_push_pending+0x6a8/0x85c net/mptcp/protocol.c:1645
 mptcp_sendmsg+0x1544/0x1a1c net/mptcp/protocol.c:1828
 inet_sendmsg+0x15c/0x290 net/ipv4/af_inet.c:828
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 ____sys_sendmsg+0x584/0x870 net/socket.c:2431
 ___sys_sendmsg+0x214/0x294 net/socket.c:2485
 __sys_sendmsg net/socket.c:2514 [inline]
 __do_sys_sendmsg net/socket.c:2523 [inline]
 __se_sys_sendmsg net/socket.c:2521 [inline]
 __arm64_sys_sendmsg+0x1ac/0x25c net/socket.c:2521
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
irq event stamp: 2012
hardirqs last  enabled at (2011): [<ffff80000832c48c>] __up_console_sem+0xb4/0x100 kernel/printk/printk.c:257
hardirqs last disabled at (2012): [<ffff8000119928bc>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:396
softirqs last  enabled at (1986): [<ffff800011944f34>] spin_unlock_bh include/linux/spinlock.h:408 [inline]
softirqs last  enabled at (1986): [<ffff800011944f34>] mptcp_wmem_alloc net/mptcp/protocol.c:1030 [inline]
softirqs last  enabled at (1986): [<ffff800011944f34>] mptcp_sendmsg+0xcf0/0x1a1c net/mptcp/protocol.c:1785
softirqs last disabled at (1984): [<ffff800011944d8c>] spin_lock_bh include/linux/spinlock.h:368 [inline]
softirqs last disabled at (1984): [<ffff800011944d8c>] mptcp_wmem_alloc net/mptcp/protocol.c:1022 [inline]
softirqs last disabled at (1984): [<ffff800011944d8c>] mptcp_sendmsg+0xb48/0x1a1c net/mptcp/protocol.c:1785
---[ end trace 53caa6a97c5d4eb8 ]---