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Biederman" Cc: Bernd Edlinger , Alexander Viro , Alexey Dobriyan , Kees Cook , Andy Lutomirski , Will Drewry , Christian Brauner , Andrew Morton , Michal Hocko , Serge Hallyn , James Morris , Randy Dunlap , Suren Baghdasaryan , Yafang Shao , Helge Deller , Adrian Reber , Thomas Gleixner , Jens Axboe , Alexei Starovoitov , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" , linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, tiozhang , Luis Chamberlain , "Paulo Alcantara (SUSE)" , Sergey Senozhatsky , Frederic Weisbecker , YueHaibing , Paul Moore , Aleksa Sarai , Stefan Roesch , Chao Yu , xu xin , Jeff Layton , Jan Kara , David Hildenbrand , Dave Chinner , Shuah Khan , Elena Reshetova , David Windsor , Mateusz Guzik , Ard Biesheuvel , "Joel Fernandes (Google)" , "Matthew Wilcox (Oracle)" , Hans Liljestrand , Penglei Jiang , Lorenzo Stoakes , Adrian Ratiu , Ingo Molnar , "Peter Zijlstra (Intel)" , Cyrill Gorcunov , Eric Dumazet Subject: Re: [RFC][PATCH] exec: Move cred computation under exec_update_lock Message-ID: References: <87tsyozqdu.fsf@email.froward.int.ebiederm.org> <87wm3ky5n9.fsf@email.froward.int.ebiederm.org> <87h5uoxw06.fsf_-_@email.froward.int.ebiederm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87h5uoxw06.fsf_-_@email.froward.int.ebiederm.org> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Stat-Signature: pjngdha7rrc3dnhysy53u96m9ym4twed X-Rspam-User: X-Rspamd-Queue-Id: 25BD140002 X-Rspamd-Server: rspam01 X-HE-Tag: 1763923968-484499 X-HE-Meta: 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 sWpgXOwI 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Eric, sorry for delay, I am on PTO, didn't read emails this week... On 11/20, Eric W. Biederman wrote: > > Instead of computing the new cred before we pass the point of no > return compute the new cred just before we use it. > > This allows the removal of fs_struct->in_exec and cred_guard_mutex. > > I am not certain why we wanted to compute the cred for the new > executable so early. Perhaps I missed something but I did not see any > common errors being signaled. So I don't think we loose anything by > computing the new cred later. > > We gain a lot. Yes. I LIKE your approach after a quick glance. And I swear, I thought about it too ;) But is it correct? I don't know. I'll try to actually read your patch next week (I am on PTO untill the end of November), but I am not sure I can provide a valuable feedback. One "obvious" problem is that, after this patch, the execing process can crash in a case when currently exec() returns an error... Oleg.