forked from TencentOS/TencentOS-kernel
b31a6a5b37
commit d966ddcc38217a6110a6a0ff37ad2dee7d42e23e upstream.
In the commit fdeba99b1e58
("tipc: fix use-after-free in tipc_bcast_get_mode"), we're trying
to make sure the tipc_net_finalize_work work item finished if it
enqueued. But calling flush_scheduled_work() is not just affecting
above work item but either any scheduled work. This has turned out
to be overkill and caused to deadlock as syzbot reported:
======================================================
WARNING: possible circular locking dependency detected
5.9.0-rc2-next-20200828-syzkaller #0 Not tainted
------------------------------------------------------
kworker/u4:6/349 is trying to acquire lock:
ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: flush_workqueue+0xe1/0x13e0 kernel/workqueue.c:2777
but task is already holding lock:
ffffffff8a879430 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x9b/0xb10 net/core/net_namespace.c:565
[...]
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(pernet_ops_rwsem);
lock(&sb->s_type->i_mutex_key#13);
lock(pernet_ops_rwsem);
lock((wq_completion)events);
*** DEADLOCK ***
[...]
v1:
To fix the original issue, we replace above calling by introducing
a bit flag. When a namespace cleaned-up, bit flag is set to zero and:
- tipc_net_finalize functionial just does return immediately.
- tipc_net_finalize_work does not enqueue into the scheduled work queue.
v2:
Use cancel_work_sync() helper to make sure ONLY the
tipc_net_finalize_work() stopped before releasing bcbase object.
Reported-by: syzbot+d5aa7e0385f6a5d0f4fd@syzkaller.appspotmail.com
Fixes: fdeba99b1e58 ("tipc: fix use-after-free in tipc_bcast_get_mode")
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Hoang Huu Le <hoang.h.le@dektech.com.au>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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|---|---|---|
| .. | ||
| Kconfig | ||
| Makefile | ||
| addr.c | ||
| addr.h | ||
| bcast.c | ||
| bcast.h | ||
| bearer.c | ||
| bearer.h | ||
| core.c | ||
| core.h | ||
| diag.c | ||
| discover.c | ||
| discover.h | ||
| eth_media.c | ||
| group.c | ||
| group.h | ||
| ib_media.c | ||
| link.c | ||
| link.h | ||
| 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.c | ||
| netlink.h | ||
| netlink_compat.c | ||
| 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 | ||