Subject: Re: [PATCH net] netdevsim: Initialize all fields of ip header when building dummy sk_buff

From: Breno Leitao <[email-masked]>
Date: Tue, 21 Apr 2026 02:12:31 -0700

On Tue, Apr 21, 2026 at 11:54:19AM +0300, Nikola Z. Ivanov wrote:
> On 4/21/26 11:19 AM, Breno Leitao wrote:
> > On Tue, Apr 21, 2026 at 10:37:38AM +0300, Nikola Z. Ivanov wrote:
> > >
> > > Closes: https://syzkaller.appspot.com/bug?extid=23d7fcd204e3837866ff
> >
> > How do you check in the report above that the missig un-initialized
> > fields are "tos" and "id"?
> 
> I don't think it is visible here, my guess would
> be because the checksum calculator walks the
> header in small chunks instead of referencing
> its fields.
> 
> The whole "KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt"
> doesn't really sound quite right.

That's precisely my question - how does this fix relate to that specific
report?

Were you able to reproduce the KMSAN report?

Thanks for the quick answer,
--breno