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82cb4e4612
syzbot found a crash in tipc_topsrv_accept:
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
Workqueue: tipc_rcv tipc_topsrv_accept
RIP: 0010:kernel_accept+0x22d/0x350 net/socket.c:3487
Call Trace:
<TASK>
tipc_topsrv_accept+0x197/0x280 net/tipc/topsrv.c:460
process_one_work+0x991/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e4/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
It was caused by srv->listener that might be set to null by
tipc_topsrv_stop() in net .exit whereas it's still used in
tipc_topsrv_accept() worker.
srv->listener is protected by srv->idr_lock in tipc_topsrv_stop(), so add
a check for srv->listener under srv->idr_lock in tipc_topsrv_accept() to
avoid the null-ptr-deref. To ensure the lsock is not released during the
tipc_topsrv_accept(), move sock_release() after tipc_topsrv_work_stop()
where it's waiting until the tipc_topsrv_accept worker to be done.
Note that sk_callback_lock is used to protect sk->sk_user_data instead of
srv->listener, and it should check srv in tipc_topsrv_listener_data_ready()
instead. This also ensures that no more tipc_topsrv_accept worker will be
started after tipc_conn_close() is called in tipc_topsrv_stop() where it
sets sk->sk_user_data to null.
Fixes:
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.. | ||
addr.c | ||
addr.h | ||
bcast.c | ||
bcast.h | ||
bearer.c | ||
bearer.h | ||
core.c | ||
core.h | ||
crypto.c | ||
crypto.h | ||
diag.c | ||
discover.c | ||
discover.h | ||
eth_media.c | ||
group.c | ||
group.h | ||
ib_media.c | ||
Kconfig | ||
link.c | ||
link.h | ||
Makefile | ||
monitor.c | ||
monitor.h | ||
msg.c | ||
msg.h | ||
name_distr.c | ||
name_distr.h | ||
name_table.c | ||
name_table.h | ||
net.c | ||
net.h | ||
netlink_compat.c | ||
netlink.c | ||
netlink.h | ||
node.c | ||
node.h | ||
socket.c | ||
socket.h | ||
subscr.c | ||
subscr.h | ||
sysctl.c | ||
topsrv.c | ||
topsrv.h | ||
trace.c | ||
trace.h | ||
udp_media.c | ||
udp_media.h |