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net: rds: don't hold sock lock when cancelling work from rds_tcp_reset_callbacks() 

[ Upstream commit a91b750fd6 ]

syzbot is reporting lockdep warning at rds_tcp_reset_callbacks() [1], for
commit ac3615e7f3 ("RDS: TCP: Reduce code duplication in
rds_tcp_reset_callbacks()") added cancel_delayed_work_sync() into a section
protected by lock_sock() without realizing that rds_send_xmit() might call
lock_sock().

We don't need to protect cancel_delayed_work_sync() using lock_sock(), for
even if rds_{send,recv}_worker() re-queued this work while __flush_work()
 from cancel_delayed_work_sync() was waiting for this work to complete,
retried rds_{send,recv}_worker() is no-op due to the absence of RDS_CONN_UP
bit.

Link: https://syzkaller.appspot.com/bug?extid=78c55c7bc6f66e53dce2 [1]
Reported-by: syzbot <syzbot+78c55c7bc6f66e53dce2@syzkaller.appspotmail.com>
Co-developed-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+78c55c7bc6f66e53dce2@syzkaller.appspotmail.com>
Fixes: ac3615e7f3 ("RDS: TCP: Reduce code duplication in rds_tcp_reset_callbacks()")
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Tetsuo Handa 2022-09-29 00:25:37 +09:00 committed by Greg Kroah-Hartman
parent 248bed1dbf
commit c380c28ab9
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
net/rds/tcp.c
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@ -166,10 +166,10 @@ void rds_tcp_reset_callbacks(struct socket *sock,
*/
atomic_set(&cp->cp_state, RDS_CONN_RESETTING);
wait_event(cp->cp_waitq, !test_bit(RDS_IN_XMIT, &cp->cp_flags));
lock_sock(osock->sk);
/* reset receive side state for rds_tcp_data_recv() for osock */
cancel_delayed_work_sync(&cp->cp_send_w);
cancel_delayed_work_sync(&cp->cp_recv_w);
lock_sock(osock->sk);
if (tc->t_tinc) {
rds_inc_put(&tc->t_tinc->ti_inc);
tc->t_tinc = NULL;