Re: [PATCH] tty: limit TCSBRKP break duration

Greg Kroah-Hartman <[email protected]> Fri, 31 Jul 2026 17:04:40 +0200
Newsgroups org.kernel.vger.linux-serial,org.kernel.vger.linux-kernel
Message-ID <2026073157-expend-unzip-cad7@gregkh>
On Fri, Jul 31, 2026 at 10:30:41PM +0800, Xincheng Wang wrote:
> Hi Greg,
> 
> Yes, it would still be user-visible.
> 
> My concern is that tty_ioctl() first multiplies the TCSBRKP argument by
> 100 before passing it to send_break(), whose duration argument is
> unsigned int. For values above UINT_MAX / 100, the current behavior uses
> the low 32 bits of the multiplied product, which can be a duration very
> different from the requested interval.
> 
> But I agree that rejecting or saturating that value would also change
> current behavior. Would you be open to a fix for this, or would you
> rather leave the path as-is?

I lost all context here :(

ANyway, keeping things as-is is always good, unless you know of a way
the current stuff is broken and you can fix it without changing any
existing users.  user apis are hard...

thanks,

greg k-h