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SubjectRe: KASAN: slab-out-of-bounds Write in tty_insert_flip_string_fixed_flag
I'm really sorry for you to wait.
Since I made a few mistakes previously, I really don't want to make a
mistake again.
Therefore I have been reading documents more carefully and learning
the approved email client (i.e., mutt).
It is almost done. I will send a patch very soon.

Again, I'm really sorry.

Best regards,
Daeryong Jeong.

On Wed, Apr 25, 2018 at 9:53 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> On Thu, Apr 19, 2018 at 09:25:08PM +0900, DaeRyong Jeong wrote:
>> The patch is attached at the end of this email and can be downloaded from here.
>> https://kiwi.cs.purdue.edu/static/race-fuzzer/tty_insert_flip_string_fixed_flag.patch
>>
>> We applied the patch to v4.16 and tested our reproducer. we can't see the
>> crash any longer.
>>
>> Our rationale is
>> - Since tty_wakeup() called by __start_tty() sends frames, call
>> tty_write_lock() before __start_tty().
>> - Since tty_write_lock() might sleep, locate tty_write_lock() before
>> spin_lock_irq(&tty->flow_lock).
>> - Since wake_up_interruptible_poll() is called by both tty_write_unlock()
>> and __start_tty(), Prevent calling wake_up_interruptible_poll() twice by
>> adding the wakeup flag to tty_write_unlock()
>>
>> If there is something that we are missing or we are wrong, please let us know.
>>
>>
>> Thank you.
>>
>> Best regards,
>> Daeryong Jeong
>>
>>
>>
>> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
>> index 63114ea..09c76d3 100644
>> --- a/drivers/tty/tty_io.c
>> +++ b/drivers/tty/tty_io.c
>> @@ -873,13 +873,15 @@ static ssize_t tty_read(struct file *file, char
>> __user *buf, size_t count,
>> return i;
>> }
>>
>> -static void tty_write_unlock(struct tty_struct *tty)
>> +void tty_write_unlock(struct tty_struct *tty, int wakeup)
>> {
>> mutex_unlock(&tty->atomic_write_lock);
>> - wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
>> + if (wakeup) {
>> + wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
>> + }
>> }
>>
>
> <snip>
>
> What ever happened to this patch, did you end up resending it in a
> non-corrupted way?
>
> thanks,
>
> greg k-h

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