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Thu, 17 Sep 2026 06:50:23 +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 P/zaAq+Nq2pieAAAD6G6ig (envelope-from ); Thu, 17 Sep 2026 06:50:23 +0000 Message-ID: <2d89b88f-863c-4e8d-839c-5e800b4c4902@suse.de> Date: Thu, 17 Sep 2026 08:50:22 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] firmware/sysfb: Fix device reference count leak in sysfb_disable() To: "Deucher, Alexander" , Wentao Liang Cc: "dri-devel@lists.freedesktop.org" , "javierm@redhat.com" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" References: <20260916073815.1972045-1-vulab@iscas.ac.cn> Content-Language: en-US From: Thomas Zimmermann Autocrypt: addr=tzimmermann@suse.de; keydata= xsBNBFs50uABCADEHPidWt974CaxBVbrIBwqcq/WURinJ3+2WlIrKWspiP83vfZKaXhFYsdg XH47fDVbPPj+d6tQrw5lPQCyqjwrCPYnq3WlIBnGPJ4/jreTL6V+qfKRDlGLWFjZcsrPJGE0 BeB5BbqP5erN1qylK9i3gPoQjXGhpBpQYwRrEyQyjuvk+Ev0K1Jc5tVDeJAuau3TGNgah4Yc hdHm3bkPjz9EErV85RwvImQ1dptvx6s7xzwXTgGAsaYZsL8WCwDaTuqFa1d1jjlaxg6+tZsB 9GluwvIhSezPgnEmimZDkGnZRRSFiGP8yjqTjjWuf0bSj5rUnTGiyLyRZRNGcXmu6hjlABEB AAHNJ1Rob21hcyBaaW1tZXJtYW5uIDx0emltbWVybWFubkBzdXNlLmRlPsLAjgQTAQgAOAIb AwULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftODH AAoJEGgNwR1TC3ojx1wH/0hKGWugiqDgLNXLRD/4TfHBEKmxIrmfu9Z5t7vwUKfwhFL6hqvo lXPJJKQpQ2z8+X2vZm/slsLn7J1yjrOsoJhKABDi+3QWWSGkaGwRJAdPVVyJMfJRNNNIKwVb U6B1BkX2XDKDGffF4TxlOpSQzdtNI/9gleOoUA8+jy8knnDYzjBNOZqLG2FuTdicBXblz0Mf vg41gd9kCwYXDnD91rJU8tzylXv03E75NCaTxTM+FBXPmsAVYQ4GYhhgFt8S2UWMoaaABLDe 7l5FdnLdDEcbmd8uLU2CaG4W2cLrUaI4jz2XbkcPQkqTQ3EB67hYkjiEE6Zy3ggOitiQGcqp j//OwE0EWznS4AEIAMYmP4M/V+T5RY5at/g7rUdNsLhWv1APYrh9RQefODYHrNRHUE9eosYb T6XMryR9hT8XlGOYRwKWwiQBoWSDiTMo/Xi29jUnn4BXfI2px2DTXwc22LKtLAgTRjP+qbU6 3Y0xnQN29UGDbYgyyK51DW3H0If2a3JNsheAAK+Xc9baj0LGIc8T9uiEWHBnCH+RdhgATnWW GKdDegUR5BkDfDg5O/FISymJBHx2Dyoklv5g4BzkgqTqwmaYzsl8UxZKvbaxq0zbehDda8lv hFXodNFMAgTLJlLuDYOGLK2AwbrS3Sp0AEbkpdJBb44qVlGm5bApZouHeJ/+n+7r12+lqdsA EQEAAcLAdgQYAQgAIAIbDBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftOH6AAoJEGgNwR1T C3ojVSkIALpAPkIJPQoURPb1VWjh34l0HlglmYHvZszJWTXYwavHR8+k6Baa6H7ufXNQtThR yIxJrQLW6rV5lm7TjhffEhxVCn37+cg0zZ3j7zIsSS0rx/aMwi6VhFJA5hfn3T0TtrijKP4A SAQO9xD1Zk9/61JWk8OysuIh7MXkl0fxbRKWE93XeQBhIJHQfnc+YBLprdnxR446Sh8Wn/2D Ya8cavuWf2zrB6cZurs048xe0UbSW5AOSo4V9M0jzYI4nZqTmPxYyXbm30Kvmz0rYVRaitYJ 4kyYYMhuULvrJDMjZRvaNe52tkKAvMevcGdt38H4KSVXAylqyQOW5zvPc4/sq9c= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Level: X-Spam-Score: -4.30 X-Spam-Flag: NO X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.993]; MIME_GOOD(-0.10)[text/plain]; FROM_HAS_DN(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; ARC_NA(0.00)[]; TO_DN_EQ_ADDR_SOME(0.00)[]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCPT_COUNT_FIVE(0.00)[6]; RCVD_COUNT_TWO(0.00)[2]; MID_RHS_MATCH_FROM(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:url,imap1.dmz-prg2.suse.org:helo,iscas.ac.cn:email,amd.com:email,suse.de:email,suse.de:mid] Hi Am 16.09.26 um 23:06 schrieb Deucher, Alexander: > Public > >> -----Original Message----- >> From: Wentao Liang >> Sent: Wednesday, September 16, 2026 3:38 AM >> To: Deucher, Alexander >> Cc: dri-devel@lists.freedesktop.org; javierm@redhat.com; linux- >> kernel@vger.kernel.org; tzimmermann@suse.de; Wentao Liang >> ; stable@vger.kernel.org >> Subject: [PATCH] firmware/sysfb: Fix device reference count leak in >> sysfb_disable() >> >> In sysfb_disable(), parent is obtained via sysfb_parent_dev(si), which calls >> screen_info_pci_dev(si) and returns a pointer to &pdev->dev with an acquired >> reference count. However, sysfb_disable() does not release this reference >> before returning, leading to a device reference leak. >> >> Fix this by checking if parent is not an ERR_PTR and calling >> put_device(parent) before releasing the mutex. >> >> Fixes: b49420d6a1ae ("video/aperture: optionally match the device in >> sysfb_disable()") >> Cc: stable@vger.kernel.org >> Signed-off-by: Wentao Liang >> --- >> drivers/firmware/sysfb.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c index >> 8833582c1883..11c5ce128a6c 100644 >> --- a/drivers/firmware/sysfb.c >> +++ b/drivers/firmware/sysfb.c >> @@ -71,9 +71,12 @@ void sysfb_disable(struct device *dev) >> >> mutex_lock(&disable_lock); >> parent = sysfb_parent_dev(si); >> - if (!dev || !parent || dev == parent) { >> - sysfb_unregister(); >> - disabled = true; >> + if (!IS_ERR(parent)) { > Are there cases where sysfb_unregister() would need to be called even if parent returns an error? It could be seen as a defensive measure. Usually we want to unregister the system framebuffer only if the native driver's device equals the parent. But if we fail to retrieve a parent, it might be better to unregister unconditionally.  Otherwise the sysfb driver might interfere with the native driver. I think that would be a good idea. Best regards Thomas > > Alex > >> + if (!dev || !parent || dev == parent) { >> + sysfb_unregister(); >> + disabled = true; >> + } >> + put_device(parent); >> } >> mutex_unlock(&disable_lock); >> } >> -- >> 2.34.1 -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)