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Tue, 12 Mar 2024 09:45:37 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id B4c3CkEk8GXFPAAAD6G6ig (envelope-from ); Tue, 12 Mar 2024 09:45:37 +0000 Date: Tue, 12 Mar 2024 10:45:28 +0100 From: Michal Hocko To: Lee Jones Cc: Luis Chamberlain , cve@kernel.org, linux-kernel@vger.kernel.org, Joel Granados , Greg Kroah-Hartman Subject: Re: CVE-2023-52596: sysctl: Fix out of bounds access for empty sysctl registers Message-ID: References: <2024030645-CVE-2023-52596-b98e@gregkh> <20240312091730.GU86322@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240312091730.GU86322@google.com> X-Spam-Level: Authentication-Results: smtp-out1.suse.de; dkim=pass header.d=suse.com header.s=susede1 header.b=Wq2U1NiO X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-5.10 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_DKIM_ALLOW(-0.20)[suse.com:s=susede1]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; DWL_DNSWL_MED(-2.00)[suse.com:dkim]; RCPT_COUNT_FIVE(0.00)[6]; NEURAL_HAM_SHORT(-0.19)[-0.953]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; DKIM_TRACE(0.00)[suse.com:+]; MX_GOOD(-0.01)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:dkim]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; MID_RHS_NOT_FQDN(0.50)[]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-2.10)[95.61%] X-Spam-Score: -5.10 X-Rspamd-Queue-Id: 52DE0374F3 X-Spam-Flag: NO On Tue 12-03-24 09:17:30, Lee Jones wrote: [...] > > Backporting this is fine, but wouldn't fix an issue unless an external > > module had empty sysctls. And exploiting this is not possible unless > > you purposely build an external module which could end up with empty > > sysctls. Thanks for the clarification Luis! > Thanks for the amazing explanation Luis. > > If I'm reading this correctly, an issue does exist, but an attacker > would have to lay some foundations before it could be triggered. Sounds > like loading of a malicious or naive module would be enough. If the bar is set as high as a kernel module to create and empty sysctl directory then I think it is safe to say that the security aspect is mostly moot. There are much simpler ways to attack the system if you are able to load a kernel module. > We know from conducting postmortems on previous exploits that successful > attacks often consist of leveraging a chain of smaller, seemingly > implausible or innocuous looking bugs rather than in isolation. > > With that in mind, it is still my belief that this could be used by an > attacker in such a chain. Unless I have this totally wrong or any of > the maintainers have strong feelings to the contrary, I would like to > keep the CVE number associated with this fix. No, no real strong feelings but I have to say that I find a CVE more than a stretch. Kernel modules could do much more harm than just abuse this particular bug. -- Michal Hocko SUSE Labs