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b=WELSnYRZeXnEsFvTMPRYAVf5j9FbHPVwByWnB+TQ24az7/mKlbden0JE61ezfx4Qz vGSp1xiA8xKoCl+uSrzfWnUdmE7PUfKM3oZCxtWdEOdUol4WdzsTwRQ3uDFL1vL2Yh XeBecTb9nAYO+B0SVj4RyFqLYvtNHk7KvALAhG68RYYZPWdbQ7AyB5ftAuzC+NFgsY 9LhE9O8gChFG/II/8R5nMzO5GO2j8CyUP2kojp7IkMZIoH0plHeUSHReq0YRHCns4j eJnRBAk79BL9bk+sjgYSvq+XxI4kslGUXwXm8VzwXevxiHop4u2OTuMmWsOUXz9Rqy R7TjCuY3wwIdQ== Date: Tue, 25 Mar 2025 15:46:15 +0100 From: Christian Brauner To: Mateusz Guzik 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 Subject: Re: [PATCH] exec: fix the racy usage of fs_struct->in_exec Message-ID: <20250325-stilbruch-deeskalation-f212bb2499de@brauner> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Queue-Id: 32A2B40015 X-Stat-Signature: x9m7y4csxfn6h6kdhwm6rw64m7tg3pjx X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1742913978-370840 X-HE-Meta: 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 KEdDRY2Z 1lvNOBJe1g1c9Lje/twJV5a1CLcuwATMgbHGn3sS3xpODVJGzsDs6Evb4KXTjKX4E5OzB/xkeqVOfUzzuYI5VilqRHtLbIROEj/GRBz6KHwPTdkJqORrlwqMPOLAOFmc//dsNxL4AdAK4Kr1+ZaQTexCR0XPSwYtaT9Qe+vmMtl7/LYeB/EWSZc2ZnqR6B/hQA5aSGsc+ytuFB6h0I7M6Q2m8joRLgAZIRKTUu8Gjv3cdQeyCh7auEqzlUDmktBLomKmoicTkP6f9j11Pu/axkj7qiobDuq7Qqd+Ip6QJLwOaBcloMSQj0nX/LktXMMTLL/MAcI+SVE9o58fZBVuKUX8byvFwlB8oSQ8p3PCO7/Nn5Oo06j4KfmvNn9AHl1eC06a7O2Vyhc63/st+Lmpzvw0F8FHuLLlP/Bzp5YLlYdJmxbZa7gMJdAioShBYmiVJT7C9TJx0cCd54L9O9ibWe3i7T+PKlrVRVnkIUt43QKjNLcAO7+R4G5GgATSZkgt07nUqlnjF7KS66CY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.001690, 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 03:15:06PM +0100, Mateusz Guzik wrote: > On Tue, Mar 25, 2025 at 2:30 PM 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 AM Oleg Nesterov wrote: > > > > > > > > > > On 03/24, Mateusz Guzik wrote: > > > > > > > > > > > > On Mon, Mar 24, 2025 at 7:28 PM 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/simplify > > > > > > > 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 expected. > > > > > > > > > > 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 week. Ok, I've taken the patch as I've got a first round of fixes to send already.