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From: Hans Verkuil <hverkuil-cisco@xs4all.nl>
To: "Yang, Chenyuan" <cy54@illinois.edu>,
	"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: "jani.nikula@intel.com" <jani.nikula@intel.com>,
	"syzkaller@googlegroups.com" <syzkaller@googlegroups.com>,
	"mchehab@kernel.org" <mchehab@kernel.org>,
	"Zhao, Zijie" <zijie4@illinois.edu>,
	"Zhang, Lingming" <lingming@illinois.edu>
Subject: Re: [Linux Kernel Bugs] KASAN: slab-use-after-free Read in cec_queue_msg_fh and 4 other crashes in the cec device (`cec_ioctl`)
Date: Tue, 30 Jan 2024 15:35:40 +0100	[thread overview]
Message-ID: <f1855145-9562-4bef-800f-43bcacff6fc8@xs4all.nl> (raw)
In-Reply-To: <526380BE-57AC-493D-A7B0-B8F0ECC0FE0A@illinois.edu>

On 29/01/2024 04:03, Yang, Chenyuan wrote:
> Hi Hans,
> 
> Thanks a lot for this new patch!
> 
> After applying this new patch in the latest kernel (hash: ecb1b8288dc7ccbdcb3b9df005fa1c0e0c0388a7) and fuzzing with Syzkaller, it seems that the hang still exists.
> To help you better debug it, I attached the covered lines for the fuzz testing and the output of `git diff`. Hope this could help you.
> 
> By the way, the syscall descriptions for CEC have been merged into the Syzkaller mainstream: https://github.com/google/syzkaller/blob/master/sys/linux/dev_cec.txt.
> 
> Let me know if you need further information.
> 
> Best,
> Chenyuan

Here is another patch. This now time outs on all wait_for_completion calls
and reports a WARN_ON and shows additional info. Hopefully this will give me
better insight into what is going on.

Unfortunately I was unable to reproduce this issue on my VM, so I have to
rely on you to run the test.

Regards,

	Hans

[PATCH] Test

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
---
diff --git a/drivers/media/cec/core/cec-adap.c b/drivers/media/cec/core/cec-adap.c
index 5741adf09a2e..b1951eb7f5bd 100644
--- a/drivers/media/cec/core/cec-adap.c
+++ b/drivers/media/cec/core/cec-adap.c
@@ -935,9 +935,12 @@ int cec_transmit_msg_fh(struct cec_adapter *adap, struct cec_msg *msg,
 	 * Release the lock and wait, retake the lock afterwards.
 	 */
 	mutex_unlock(&adap->lock);
-	wait_for_completion_killable(&data->c);
-	if (!data->completed)
-		cancel_delayed_work_sync(&data->work);
+	if (WARN_ON(wait_for_completion_killable_timeout(&data->c, msecs_to_jiffies(adap->xfer_timeout_ms + 1000)) <= 0)) {
+		dprintk(0, "wfc1: %px %d%d%d%d %x\n", adap->kthread_config,
+			adap->is_configuring, adap->is_configured,
+			adap->is_enabled, adap->must_reconfigure, adap->phys_addr);
+	}
+	cancel_delayed_work_sync(&data->work);
 	mutex_lock(&adap->lock);

 	/* Cancel the transmit if it was interrupted */
@@ -1563,10 +1566,12 @@ static int cec_config_thread_func(void *arg)
 			cec_transmit_msg_fh(adap, &msg, NULL, false);
 		}
 	}
+	mutex_unlock(&adap->lock);
+    call_void_op(adap, configured);
+    mutex_lock(&adap->lock);
 	adap->kthread_config = NULL;
 	complete(&adap->config_completion);
 	mutex_unlock(&adap->lock);
-	call_void_op(adap, configured);
 	return 0;

 unconfigure:
@@ -1592,6 +1597,17 @@ static void cec_claim_log_addrs(struct cec_adapter *adap, bool block)
 	if (WARN_ON(adap->is_configuring || adap->is_configured))
 		return;

+	if (adap->kthread_config) {
+		mutex_unlock(&adap->lock);
+//		wait_for_completion(&adap->config_completion);
+		if (WARN_ON(wait_for_completion_killable_timeout(&adap->config_completion, msecs_to_jiffies(10000)) <= 0)) {
+			dprintk(0, "wfc2: %px %d%d%d%d %x\n", adap->kthread_config,
+				adap->is_configuring, adap->is_configured,
+				adap->is_enabled, adap->must_reconfigure, adap->phys_addr);
+		}
+		mutex_lock(&adap->lock);
+	}
+
 	init_completion(&adap->config_completion);

 	/* Ready to kick off the thread */
@@ -1599,11 +1615,17 @@ static void cec_claim_log_addrs(struct cec_adapter *adap, bool block)
 	adap->kthread_config = kthread_run(cec_config_thread_func, adap,
 					   "ceccfg-%s", adap->name);
 	if (IS_ERR(adap->kthread_config)) {
-		adap->kthread_config = NULL;
 		adap->is_configuring = false;
+		adap->kthread_config = NULL;
 	} else if (block) {
 		mutex_unlock(&adap->lock);
-		wait_for_completion(&adap->config_completion);
+		//wait_for_completion(&adap->config_completion);
+		if (WARN_ON(wait_for_completion_killable_timeout(&adap->config_completion, msecs_to_jiffies(10000)) <= 0)) {
+			dprintk(0, "wfc3: %px %d%d%d%d %x\n", adap->kthread_config,
+				adap->is_configuring, adap->is_configured,
+				adap->is_enabled, adap->must_reconfigure, adap->phys_addr);
+
+		}
 		mutex_lock(&adap->lock);
 	}
 }
diff --git a/drivers/media/cec/core/cec-api.c b/drivers/media/cec/core/cec-api.c
index 67dc79ef1705..d64bb716f9c6 100644
--- a/drivers/media/cec/core/cec-api.c
+++ b/drivers/media/cec/core/cec-api.c
@@ -664,6 +664,8 @@ static int cec_release(struct inode *inode, struct file *filp)
 		list_del_init(&data->xfer_list);
 	}
 	mutex_unlock(&adap->lock);
+
+	mutex_lock(&fh->lock);
 	while (!list_empty(&fh->msgs)) {
 		struct cec_msg_entry *entry =
 			list_first_entry(&fh->msgs, struct cec_msg_entry, list);
@@ -681,6 +683,7 @@ static int cec_release(struct inode *inode, struct file *filp)
 			kfree(entry);
 		}
 	}
+	mutex_unlock(&fh->lock);
 	kfree(fh);

 	cec_put_device(devnode);


  reply	other threads:[~2024-01-30 14:35 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-28  2:33 [Linux Kernel Bugs] KASAN: slab-use-after-free Read in cec_queue_msg_fh and 4 other crashes in the cec device (`cec_ioctl`) Yang, Chenyuan
2023-12-29  6:23 ` Dmitry Vyukov
     [not found] ` <SN6PR11MB345527101A2C8A1AC99B04B5FA712@SN6PR11MB3455.namprd11.prod.outlook.com>
2024-01-18  7:52   ` Hans Verkuil
2024-01-19  8:17 ` Hans Verkuil
2024-01-22 19:11   ` Yang, Chenyuan
2024-01-23  8:02     ` Hans Verkuil
2024-01-23 10:39       ` Hans Verkuil
2024-01-24 13:33   ` Yang, Chenyuan
2024-01-25 10:35     ` Hans Verkuil
2024-01-29  3:03   ` Yang, Chenyuan
2024-01-30 14:35     ` Hans Verkuil [this message]
2024-02-12 14:42       ` Hans Verkuil
2024-02-13 15:40         ` Yang, Chenyuan
2024-02-13 16:05           ` Yang, Chenyuan
2024-02-23 14:44           ` Hans Verkuil
     [not found]             ` <PH7PR11MB5768B0BC3C042A6EA4EC1EF0A0542@PH7PR11MB5768.namprd11.prod.outlook.com>
2024-02-26 12:27               ` Yang, Chenyuan
2024-04-19 14:51                 ` Takashi Iwai
2024-04-22 12:14                   ` Hans Verkuil
2024-04-22 19:30                     ` Takashi Iwai
2024-04-22 15:04                 ` Hans Verkuil
2024-04-22 18:54                   ` Yang, Chenyuan
2024-04-22 20:57                     ` Hans Verkuil
2024-04-29 15:42                       ` Yang, Chenyuan
2024-04-30 10:26                         ` Hans Verkuil
2024-04-30 17:06                           ` Yang, Chenyuan

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