linux-kernel - Re: [GIT PULL] hardening fixes for v6.16-rc1

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Message-ID: <202505312229.DE917E6D@keescook>
Date: Sat, 31 May 2025 22:42:36 -0700
From: Kees Cook <kees@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Konstantin Ryabitsev <konstantin@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, Eric Biggers <ebiggers@...nel.org>,
	Ingo Saitz <ingo@...nover.ccc.de>,
	kernel test robot <oliver.sang@...el.com>,
	Marco Elver <elver@...gle.com>,
	Nathan Chancellor <nathan@...nel.org>,
	Thiago Jung Bauermann <thiago.bauermann@...aro.org>
Subject: Re: [GIT PULL] hardening fixes for v6.16-rc1

On Sat, May 31, 2025 at 07:35:45PM -0700, Linus Torvalds wrote:
> On Sat, 31 May 2025 at 18:06, Kees Cook <kees@...nel.org> wrote:
> >
> > I have no idea. I had noticed a bunch of my trees were refusing to have sane merges.
> 
> The rebased history would explain that, but the reason I'm upset about
> it is that I don't even see how that rebasing could possibly happen
> "by mistake".
> 
> Any normal git merge rebasing should re-write the committer. So to get
> the kinds of rewritten history that I saw, it almost has to be
> intentional. I don't see how that has happened by mistake.
> 
> At a minimum there is some truly effed up scripting going on.

Well, I didn't do it on purpose. I think I have an established track
record of asking you first before I intentionally do stupid things with
git (like the recent prefix collision PoC[1] that I privately emailed
you about).

I'm trying to figure it out now. I must have shot myself in the foot
somewhere, since I had a number of "by hand" things going on this week.
My current guess (while AFK) was that something went sideways while
trying to rebase my for-next/hardening vs my for-linus/hardening trees,
since I had, at one point, based my for-next on
9d7a0577c9db35c4cc52db90bc415ea248446472 (1 commit past v6.15-rc3) since
I was still working on -Wunterminated-string-initialization patches.
(Normally I exclusively base on -rc2.) Then I had my SSD failure, but
things seemed okay after that, but then when I built the
for-linus/hardening tree I rebased patches that were on top of for-next
over on to latest "master" because basing it on 1 past rc3 seemed weird.
It was around here that I started having problems.

But like I said, I'll see if I can reproduce it. I have a lot of
scripting to sanity check my pushes, and I (stupidly) overrode them
because normally they get angry when I'm not basing on rc2, etc. But
I've never had anything like this happen.

-Kees

[1] https://people.kernel.org/kees/colliding-with-the-sha-prefix-of-linuxs-initial-git-commit

-- 
Kees Cook