Re: [PATCH] stable: crypto: sha256 - fix crash at kexec

[Breno Leitao]

Hello Eric,

On Wed, Oct 01, 2025 at 09:54:55AM -0700, Eric Biggers wrote:
> On Wed, Oct 01, 2025 at 09:45:07AM -0700, Breno Leitao wrote:
> > Hello Eric,
> > 
> > On Wed, Oct 01, 2025 at 09:23:05AM -0700, Eric Biggers wrote:
> > 
> > > This looks fine, but technically 'unsigned int' would be more
> > > appropriate here, given the context.  If we look at the whole function
> > > in 6.12, we can see that it took an 'unsigned int' length:
> > 
> > Ack. Do you want me to send a v2 with `unsigned int` instead?
> > 
> 
> Sure.  Could you also make it clear which kernel version(s) you are
> expecting the patch to be applied to?  Is it everything 5.4 through
> 6.15?  It looks like this bug actually got exposed by f4da7afe07523f
> ("kexec_file: increase maximum file size to 4G") in 6.0.

Good point. I've put my wanna-be-hacker hat and try to crash the host
before commit f4da7afe07523f ("kexec_file: increase maximum file size to
4G"), but no luck at all.

So, I would say we want to limit the backport from v6.0 to 6.16. In
this case, it seems the easiest thing for stable maintainers is to
"Fixes: f4da7afe07523f ("kexec_file: increase maximum file size to
4G")", which will limit the backport into only affected kernels.

Let me send a v2 and we can catch-up there.

Thanks for finding f4da7afe07523f!
--breno