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Message-ID: <2e5f1e92-7fad-4a74-b375-1e194ff08ce6@xs4all.nl>
Date: Mon, 12 Feb 2024 15:42:39 +0100
From: Hans Verkuil <hverkuil-cisco@...all.nl>
To: "Yang, Chenyuan" <cy54@...inois.edu>,
"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc: "jani.nikula@...el.com" <jani.nikula@...el.com>,
"syzkaller@...glegroups.com" <syzkaller@...glegroups.com>,
"mchehab@...nel.org" <mchehab@...nel.org>, "Zhao, Zijie"
<zijie4@...inois.edu>, "Zhang, Lingming" <lingming@...inois.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`)
Hi Chenyuan,
On 30/01/2024 15:35, Hans Verkuil wrote:
> 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.
Did you have time to run the test with this patch? It would be very useful to
see the results.
Regards,
Hans
>
> Regards,
>
> Hans
>
> [PATCH] Test
>
> Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.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);
>
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