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`)
From: Hans Verkuil
Date: Mon Apr 22 2024 - 08:14:29 EST
Hi Takashi,
On 19/04/2024 16:51, Takashi Iwai wrote:
> On Mon, 26 Feb 2024 13:27:16 +0100,
> Yang, Chenyuan wrote:
>>
>> Hi Hans,
>>
>> Thank you for your continued efforts in investigating this bug and implementing the new patch!
>>
>> Regarding the two warnings, they have been addressed by this new patch and are no longer reproducible. Additionally, I conducted a 48-hour fuzzing test on the CEC driver, which has successfully eliminated the previous hanging issue.
>>
>> One thing to note that the system will now log timeout events:
>> ```
>> [ 2281.265385][ T2034] cec-vivid-001-vid-out0: transmit timed out
>> [ 2282.994510][ T2017] cec-vivid-000-vid-cap0: transmit timed out
>> [ 2283.063484][ T2050] cec-vivid-002-vid-out0: transmit timed out
>> [ 2283.073468][ T2065] cec-vivid-003-vid-cap0: transmit timed out
>> [ 2283.373518][ T2033] cec-vivid-001-vid-cap0: transmit timed out
>> [ 2285.113544][ T2018] cec-vivid-000-vid-out0: transmit timed out
>> [ 2285.193502][ T2050] cec-vivid-002-vid-out0: transmit timed out
>> [ 2285.193570][ T2065] cec-vivid-003-vid-cap0: transmit timed out
>> [ 2285.513570][ T2033] cec-vivid-001-vid-cap0: transmit timed out
>> ```
>>
>> Best,
>> Chenyuan
>
> Hi Hans,
>
> how is the current status of this bug fix? It seems that the thread
> stalled, and I wonder how we can go further.
>
> I'm asking it because CVE-2024-23848 was assigned and we've been asked
> about the bug fix.
I missed this reply, so I will take another look at the patch. Too many emails :-(
Two other patches relating to this I have just posted:
https://patchwork.linuxtv.org/project/linux-media/patch/2b043325-14c0-4e63-ae9c-0d685d96fd98@xxxxxxxxx/
https://patchwork.linuxtv.org/project/linux-media/patch/f17f961b-3a19-48da-941a-c8970d9e1786@xxxxxxxxx/
Regards,
Hans
>
>
> Thanks!
>
> Takashi
>
>>
>> From: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
>> Date: Friday, February 23, 2024 at 8:44 AM
>> To: Yang, Chenyuan <cy54@xxxxxxxxxxxx>, linux-media@xxxxxxxxxxxxxxx <linux-media@xxxxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx <linux-kernel@xxxxxxxxxxxxxxx>
>> Cc: jani.nikula@xxxxxxxxx <jani.nikula@xxxxxxxxx>, syzkaller@xxxxxxxxxxxxxxxx <syzkaller@xxxxxxxxxxxxxxxx>, mchehab@xxxxxxxxxx <mchehab@xxxxxxxxxx>, Zhao, Zijie <zijie4@xxxxxxxxxxxx>, Zhang, Lingming <lingming@xxxxxxxxxxxx>
>> 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,
>>
>> Here is another patch for you to try. I think it is good for blocking CEC_ADAP_S_LOG_ADDRS
>> ioctl calls, but if the filehandle is in non-blocking mode, I'm still not certain it
>> is correct. But one issue at a time :-)
>>
>> Regards,
>>
>> Hans
>>
>> diff --git a/drivers/media/cec/core/cec-adap.c b/drivers/media/cec/core/cec-adap.c
>> index 559a172ebc6c..a493cbce2456 100644
>> --- a/drivers/media/cec/core/cec-adap.c
>> +++ b/drivers/media/cec/core/cec-adap.c
>> @@ -936,8 +936,7 @@ int cec_transmit_msg_fh(struct cec_adapter *adap, struct cec_msg *msg,
>> */
>> mutex_unlock(&adap->lock);
>> wait_for_completion_killable(&data->c);
>> - if (!data->completed)
>> - cancel_delayed_work_sync(&data->work);
>> + cancel_delayed_work_sync(&data->work);
>> mutex_lock(&adap->lock);
>>
>> /* Cancel the transmit if it was interrupted */
>> @@ -1575,9 +1574,12 @@ static int cec_config_thread_func(void *arg)
>> */
>> static void cec_claim_log_addrs(struct cec_adapter *adap, bool block)
>> {
>> - if (WARN_ON(adap->is_configuring || adap->is_configured))
>> + if (WARN_ON(adap->is_claiming_log_addrs ||
>> + adap->is_configuring || adap->is_configured))
>> return;
>>
>> + adap->is_claiming_log_addrs = true;
>> +
>> init_completion(&adap->config_completion);
>>
>> /* Ready to kick off the thread */
>> @@ -1592,6 +1594,7 @@ static void cec_claim_log_addrs(struct cec_adapter *adap, bool block)
>> wait_for_completion(&adap->config_completion);
>> mutex_lock(&adap->lock);
>> }
>> + adap->is_claiming_log_addrs = false;
>> }
>>
>> /*
>> diff --git a/drivers/media/cec/core/cec-api.c b/drivers/media/cec/core/cec-api.c
>> index 67dc79ef1705..3ef915344304 100644
>> --- a/drivers/media/cec/core/cec-api.c
>> +++ b/drivers/media/cec/core/cec-api.c
>> @@ -178,7 +178,7 @@ static long cec_adap_s_log_addrs(struct cec_adapter *adap, struct cec_fh *fh,
>> CEC_LOG_ADDRS_FL_ALLOW_RC_PASSTHRU |
>> CEC_LOG_ADDRS_FL_CDC_ONLY;
>> mutex_lock(&adap->lock);
>> - if (!adap->is_configuring &&
>> + if (!adap->is_claiming_log_addrs && !adap->is_configuring &&
>> (!log_addrs.num_log_addrs || !adap->is_configured) &&
>> !cec_is_busy(adap, fh)) {
>> err = __cec_s_log_addrs(adap, &log_addrs, block);
>> @@ -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);
>> diff --git a/include/media/cec.h b/include/media/cec.h
>> index 10c9cf6058b7..cc3fcd0496c3 100644
>> --- a/include/media/cec.h
>> +++ b/include/media/cec.h
>> @@ -258,6 +258,7 @@ struct cec_adapter {
>> u16 phys_addr;
>> bool needs_hpd;
>> bool is_enabled;
>> + bool is_claiming_log_addrs;
>> bool is_configuring;
>> bool must_reconfigure;
>> bool is_configured;
>>