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From: Duoming Zhou <duoming@zju.edu.cn>
To: linux-sctp@vger.kernel.org
Cc: vyasevich@gmail.com, nhorman@tuxdriver.com,
	marcelo.leitner@gmail.com, davem@davemloft.net,
	edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Duoming Zhou <duoming@zju.edu.cn>
Subject: [PATCH net] sctp: fix sleep in atomic context bug in timer handlers
Date: Sat, 23 Jul 2022 09:58:09 +0800	[thread overview]
Message-ID: <20220723015809.11553-1-duoming@zju.edu.cn> (raw)

There are sleep in atomic context bugs in timer handlers of sctp
such as sctp_generate_t3_rtx_event(), sctp_generate_probe_event(),
sctp_generate_t1_init_event(), sctp_generate_timeout_event(),
sctp_generate_t3_rtx_event() and so on.

The root cause is sctp_sched_prio_init_sid() with GFP_KERNEL parameter
that may sleep could be called by different timer handlers which is in
interrupt context.

One of the call paths that could trigger bug is shown below:

      (interrupt context)
sctp_generate_probe_event
  sctp_do_sm
    sctp_side_effects
      sctp_cmd_interpreter
        sctp_outq_teardown
          sctp_outq_init
            sctp_sched_set_sched
              n->init_sid(..,GFP_KERNEL)
                sctp_sched_prio_init_sid //may sleep

This patch changes gfp_t parameter of init_sid in sctp_sched_set_sched()
from GFP_KERNEL to GFP_ATOMIC in order to prevent sleep in atomic
context bugs.

Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
---
 net/sctp/stream_sched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sctp/stream_sched.c b/net/sctp/stream_sched.c
index 518b1b9bf89..1ad565ed562 100644
--- a/net/sctp/stream_sched.c
+++ b/net/sctp/stream_sched.c
@@ -160,7 +160,7 @@ int sctp_sched_set_sched(struct sctp_association *asoc,
 		if (!SCTP_SO(&asoc->stream, i)->ext)
 			continue;
 
-		ret = n->init_sid(&asoc->stream, i, GFP_KERNEL);
+		ret = n->init_sid(&asoc->stream, i, GFP_ATOMIC);
 		if (ret)
 			goto err;
 	}
-- 
2.17.1


             reply	other threads:[~2022-07-23  1:58 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-23  1:58 Duoming Zhou [this message]
2022-07-24 13:13 ` Marcelo Ricardo Leitner
2022-07-26  2:50 ` patchwork-bot+netdevbpf

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