Re: [PATCH 4.14 17/89] futex: Prevent overflow by strengthen input validation

[Greg Kroah-Hartman]

On Thu, Jan 25, 2018 at 03:47:32PM +0100, Jiri Slaby wrote:
> On 01/25/2018, 03:30 PM, Thomas Gleixner wrote:
> > So what's the problem?
> 
> The problem I see is that every stable kernel now requires updated
> strace with their commit from yesterday to build correctly. In
> particular, the new stable kernels cause rpm build failures of strace in
> all our distros (based on those stable kernels). Sure, we can patch
> strace in every distro every nth kernel update, but it's mere
> impractical. Kernel should not break userspace, right?

Well, when userspace is doing something stupid... :)

> BTW why was the patch applied to stable? We actually do pass
> -fno-strict-overflow.

The same reason it was applied upstream, it fixes a reported
issue.

Does that mean that all UBSAN overflow error reports are not valid
because of how we build the kernel?

thanks,

greg k-h