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Message-ID: <tencent_941B48254CBA00BB4933069E391B6E4B5408@qq.com>
From: Edward Adam Davis <eadavis@qq.com>
To: syzbot+116b65a23bc791ae49a6@syzkaller.appspotmail.com
Cc: hverkuil-cisco@xs4all.nl,
	linux-kernel@vger.kernel.org,
	linux-media@vger.kernel.org,
	mchehab@kernel.org,
	syzkaller-bugs@googlegroups.com
Subject: [PATCH] media/cec/core: fix task hung in cec_claim_log_addrs
Date: Wed, 21 Feb 2024 22:20:05 +0800
In-Reply-To: <0000000000006d96200611de3986@google.com>
References: <0000000000006d96200611de3986@google.com>
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After unlocking adap->lock in cec_claim_log_addrs(), cec_claim_log_addrs() may
re-enter, causing this issue to occur.

In the thread function cec_config_thread_func() adap->lock is also used, so there
is no need to unlock adap->lock in cec_claim_log_addrs(), and then use adap->lock
in cec_config_thread_func() to protect.

Reported-and-tested-by: syzbot+116b65a23bc791ae49a6@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 drivers/media/cec/core/cec-adap.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/media/cec/core/cec-adap.c b/drivers/media/cec/core/cec-adap.c
index 5741adf09a2e..21b3ff504524 100644
--- a/drivers/media/cec/core/cec-adap.c
+++ b/drivers/media/cec/core/cec-adap.c
@@ -1436,7 +1436,6 @@ static int cec_config_thread_func(void *arg)
 	int err;
 	int i, j;
 
-	mutex_lock(&adap->lock);
 	dprintk(1, "physical address: %x.%x.%x.%x, claim %d logical addresses\n",
 		cec_phys_addr_exp(adap->phys_addr), las->num_log_addrs);
 	las->log_addr_mask = 0;
@@ -1565,7 +1564,6 @@ static int cec_config_thread_func(void *arg)
 	}
 	adap->kthread_config = NULL;
 	complete(&adap->config_completion);
-	mutex_unlock(&adap->lock);
 	call_void_op(adap, configured);
 	return 0;
 
@@ -1577,7 +1575,6 @@ static int cec_config_thread_func(void *arg)
 	adap->must_reconfigure = false;
 	adap->kthread_config = NULL;
 	complete(&adap->config_completion);
-	mutex_unlock(&adap->lock);
 	return 0;
 }
 
@@ -1602,9 +1599,7 @@ static void cec_claim_log_addrs(struct cec_adapter *adap, bool block)
 		adap->kthread_config = NULL;
 		adap->is_configuring = false;
 	} else if (block) {
-		mutex_unlock(&adap->lock);
 		wait_for_completion(&adap->config_completion);
-		mutex_lock(&adap->lock);
 	}
 }
 
-- 
2.43.0