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Wed, 17 Sep 2025 11:04:52 +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 9hgdLdSVymiiQgAAD6G6ig (envelope-from ); Wed, 17 Sep 2025 11:04:52 +0000 Date: Wed, 17 Sep 2025 13:04:50 +0200 From: Jean Delvare To: "Michael J. Ruhl" Cc: Andy Shevchenko , Andi Shyti , Jarkko Nikula , Mika Westerberg , Jan Dabros , linux-i2c@vger.kernel.org Subject: Recent i2c-designware initialization fix Message-ID: <20250917130450.50ff0db3@endymion> Organization: SUSE Linux X-Mailer: Claws Mail 4.2.0 (GTK 3.24.43; x86_64-suse-linux-gnu) Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Spamd-Result: default: False [-4.01 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_RHS_NOT_FQDN(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FUZZY_RATELIMITED(0.00)[rspamd.com]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; HAS_ORG_HEADER(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_SEVEN(0.00)[7]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+] X-Spam-Flag: NO X-Spam-Level: X-Rspamd-Queue-Id: 21EC721CF7 X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -4.01 Hello Michael, I have been looking into your kernel commit 3d30048958e0 ("i2c/designware: Fix an initialization issue"), as it received a CVE number (CVE-2025-38380), I was asked to evaluate the severity of the bug. I was not familiar with the i2c-designware driver so it took me some reading time to form an opinion on the matter. But after a careful review, my conclusion is that there was no actual bug in the first place. If I'm correct then CVE-2025-38380 is invalid. My reasoning is as follows: * struct dw_i2c_dev is allocated per-PCI device in i2c_dw_pci_probe() using devm_kzalloc(), therefore all its members, including dev->msg_write_idx, are initialized to 0. * The supposedly problematic code path is only taken if (dev->flags & MODEL_MASK) == MODEL_AMD_NAVI_GPU. * The only place where dev->msg_write_idx is set to a non-zero value is in i2c_dw_xfer_msg(). This function is only called by i2c_dw_isr(), which in turn is only called if the device is not in polling mode. * The flags set for the AMD Navi GPU devices are: dev->flags |= MODEL_AMD_NAVI_GPU | ACCESS_POLLING so these devices are always in polling mode and never use an interrupt so i2c_dw_isr() is never called for them. If my reasoning is correct, then for the AMD Navi GPU devices, dev->msg_write_idx is implicitly initialized to 0 at allocation time and its value is never changed after that, so the explicit initialization to 0 which has been added in amd_i2c_dw_xfer_quirk() is a no-op. What do you think? Am I missing something? Thanks, -- Jean Delvare SUSE L3 Support