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Tue, 25 Mar 2025 07:15:19 -0700 (PDT) MIME-Version: 1.0 References: <67dc67f0.050a0220.25ae54.001f.GAE@google.com> <20250324160003.GA8878@redhat.com> <20250324182722.GA29185@redhat.com> <20250325100936.GC29185@redhat.com> <20250325132136.GB7904@redhat.com> <20250325-bretter-anfahren-39ee9eedf048@brauner> In-Reply-To: <20250325-bretter-anfahren-39ee9eedf048@brauner> From: Mateusz Guzik Date: Tue, 25 Mar 2025 15:15:06 +0100 X-Gm-Features: AQ5f1Jr8oXwwdmvGSBUITgwEGjTjEUXxS32Qqv2Kn_lvnq3BY7I5kPchOqLOEt8 Message-ID: Subject: Re: [PATCH] exec: fix the racy usage of fs_struct->in_exec To: Christian Brauner Cc: Oleg Nesterov , syzbot , kees@kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 27CC91C002D X-Stat-Signature: bupw5cfmmucm4s6kuy17bcmk669zbwi8 X-HE-Tag: 1742912121-107461 X-HE-Meta: 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 Arrsv0Oy 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.080337, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 25, 2025 at 2:30=E2=80=AFPM Christian Brauner wrote: > > On Tue, Mar 25, 2025 at 02:21:36PM +0100, Oleg Nesterov wrote: > > On 03/25, Mateusz Guzik wrote: > > > > > > On Tue, Mar 25, 2025 at 11:10=E2=80=AFAM Oleg Nesterov wrote: > > > > > > > > On 03/24, Mateusz Guzik wrote: > > > > > > > > > > On Mon, Mar 24, 2025 at 7:28=E2=80=AFPM Oleg Nesterov wrote: > > > > > > > > > > > > So to me it would be better to have the trivial fix for stable, > > > > > > exactly because it is trivially backportable. Then cleanup/simp= lify > > > > > > this logic on top of it. > > > > > > > > > > So I got myself a crap testcase with a CLONE_FS'ed task which can > > > > > execve and sanity-checked that suid is indeed not honored as expe= cted. > > > > > > > > So you mean my patch can't fix the problem? > > > > > > No, I think the patch works. > > > > > > I am saying the current scheme is avoidably hard to reason about. > > > > Ah, OK, thanks. Then I still think it makes more sense to do the > > cleanups you propose on top of this fix. > > I agree. We should go with Oleg's fix that in the old scheme and use > that. And then @Mateusz your cleanup should please go on top! Ok, in that case I'm gonna ship when I'm gonna ship(tm), maybe later this w= eek. --=20 Mateusz Guzik