From nobody Sun Apr 5 18:20:21 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D4FBD26B2D7; Tue, 24 Mar 2026 01:00:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774314060; cv=none; b=EQc3zpUBXNJx+IVvDbes/DUtX2zOLM4+vcxlk9tuqFWP+ar+Z4dzgQj6Ad+DcB5OjEoCmicvsnm/KZo30I11IvJNiv3IRmB1iGwTboE1v/nSuJ+xRNOrQ2tNuKn3qwI0LFUTLyRAupGS3xEVpF7uTGxxDWerqxRqZ5Ib10gzhT8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774314060; c=relaxed/simple; bh=ByobimVvZngWYiBS4MISNoCZaILbn7MyP0EmUHxONX8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MWKcbVTBAEbeqdJiexodqk7aQQzR0bdjo5y8066l/A6nKTofZr0Nr9u5OJTA7t+IuWIUbYeHJkRACSnUJOBSRkpr98cPoiKw5hBp4XNdgV/fnYIgC6c5BwSALn2/730CYj9G/pyg0i8JZPhBd1+sOL59E9am07KNVicMVaNO5vI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M5cmM+6D; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="M5cmM+6D" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F37F1C4CEF7; Tue, 24 Mar 2026 01:00:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774314059; bh=ByobimVvZngWYiBS4MISNoCZaILbn7MyP0EmUHxONX8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=M5cmM+6DyqmK+EAGRvLHS/yaDqvmCvw5jU4r7SCyXiBwcQBFFqbb4X/i4pXN2bi2S gHkRbl+Xo3RELYoiG4jfGiG71cPBeRkIjOhdvO7LyCtTJjVMWWsggEZfDrMHEQh/LT sJPml12ZLm2ZXWcUV7+rSBuPDv4wlXIGpfa5Mp3UMgF0NSXsREGrGnuvEljzT3nxKU rRCqRHzFA+L/AZEsNVivSFaFs9zyzzt9OOmEyPjs+2mnPiQ4PBAEg9i9nAYF6+ohUT 5vkv2XGga3nnGd1hHPKmfzckD1wY8wwkbKkdLTe4mZgsX9KBZZceAs6EiZe7MaJYyF N2W+3BMlOYL3w== From: Danilo Krummrich To: Russell King , Greg Kroah-Hartman , "Rafael J. Wysocki" , Ioana Ciornei , Nipun Gupta , Nikhil Agarwal , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Bjorn Helgaas , Armin Wolf , Bjorn Andersson , Mathieu Poirier , Vineeth Vijayan , Peter Oberparleiter , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Harald Freudenberger , Holger Dengler , Mark Brown , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Alex Williamson , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , "Christophe Leroy (CS GROUP)" Cc: linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, linux-spi@vger.kernel.org, virtualization@lists.linux.dev, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, linux-arm-kernel@lists.infradead.org, Danilo Krummrich , Gui-Dong Han Subject: [PATCH 09/12] s390/cio: use generic driver_override infrastructure Date: Tue, 24 Mar 2026 01:59:13 +0100 Message-ID: <20260324005919.2408620-10-dakr@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260324005919.2408620-1-dakr@kernel.org> References: <20260324005919.2408620-1-dakr@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When a driver is probed through __driver_attach(), the bus' match() callback is called without the device lock held, thus accessing the driver_override field without a lock, which can cause a UAF. Fix this by using the driver-core driver_override infrastructure taking care of proper locking internally. Note that calling match() from __driver_attach() without the device lock held is intentional. [1] Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel= .org/ [1] Reported-by: Gui-Dong Han Closes: https://bugzilla.kernel.org/show_bug.cgi?id=3D220789 Fixes: ebc3d1791503 ("s390/cio: introduce driver_override on the css bus") Signed-off-by: Danilo Krummrich Reviewed-by: Vineeth Vijayan --- drivers/s390/cio/cio.h | 5 ----- drivers/s390/cio/css.c | 34 ++++------------------------------ 2 files changed, 4 insertions(+), 35 deletions(-) diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h index 08a5e9380e75..bad142c536e1 100644 --- a/drivers/s390/cio/cio.h +++ b/drivers/s390/cio/cio.h @@ -103,11 +103,6 @@ struct subchannel { struct work_struct todo_work; struct schib_config config; u64 dma_mask; - /* - * Driver name to force a match. Do not set directly, because core - * frees it. Use driver_set_override() to set or clear it. - */ - const char *driver_override; } __attribute__ ((aligned(8))); =20 DECLARE_PER_CPU_ALIGNED(struct irb, cio_irb); diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index 5ab239f38588..e5a0ec6b4e3e 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -159,7 +159,6 @@ static void css_subchannel_release(struct device *dev) =20 sch->config.intparm =3D 0; cio_commit_config(sch); - kfree(sch->driver_override); kfree(sch); } =20 @@ -323,37 +322,9 @@ static ssize_t modalias_show(struct device *dev, struc= t device_attribute *attr, =20 static DEVICE_ATTR_RO(modalias); =20 -static ssize_t driver_override_store(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) -{ - struct subchannel *sch =3D to_subchannel(dev); - int ret; - - ret =3D driver_set_override(dev, &sch->driver_override, buf, count); - if (ret) - return ret; - - return count; -} - -static ssize_t driver_override_show(struct device *dev, - struct device_attribute *attr, char *buf) -{ - struct subchannel *sch =3D to_subchannel(dev); - ssize_t len; - - device_lock(dev); - len =3D sysfs_emit(buf, "%s\n", sch->driver_override); - device_unlock(dev); - return len; -} -static DEVICE_ATTR_RW(driver_override); - static struct attribute *subch_attrs[] =3D { &dev_attr_type.attr, &dev_attr_modalias.attr, - &dev_attr_driver_override.attr, NULL, }; =20 @@ -1356,9 +1327,11 @@ static int css_bus_match(struct device *dev, const s= truct device_driver *drv) struct subchannel *sch =3D to_subchannel(dev); const struct css_driver *driver =3D to_cssdriver(drv); struct css_device_id *id; + int ret; =20 /* When driver_override is set, only bind to the matching driver */ - if (sch->driver_override && strcmp(sch->driver_override, drv->name)) + ret =3D device_match_driver_override(dev, drv); + if (ret =3D=3D 0) return 0; =20 for (id =3D driver->subchannel_type; id->match_flags; id++) { @@ -1415,6 +1388,7 @@ static int css_uevent(const struct device *dev, struc= t kobj_uevent_env *env) =20 static const struct bus_type css_bus_type =3D { .name =3D "css", + .driver_override =3D true, .match =3D css_bus_match, .probe =3D css_probe, .remove =3D css_remove, --=20 2.53.0