From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 C3BCE4F5E0; Wed, 20 May 2026 18:00:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779300040; cv=none; b=nEy3mPaRHbub8tRjB8yFnuCSlkpBBf6OiY31VvMWyeyKWdtsRSEObPlqSE/vx6a8EHlJFfaCIkWk67IN4i1o5HjIqBRSFX7haz7+Qb7o3Gd+5lhgpc6YugealCBd/LkkXu68SPMKFl0l8TsKJBnZRRXs3VxjNuG4pzpqCRCv9qs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779300040; c=relaxed/simple; bh=p74XBqEvUsSo+S/2/1mo23Ntjx53CvEd/wNlHE5yLUE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bI6HjXBsqAaMW1TVpaFfO+ys0KiZIk5z5YCGef1xJM+ugw6VfsiWAGRyWS/GUTWv0ZSqy+F+2de7W7e62VXo4cRGvRpghh4m33BKvbLUanI29Ua1eRR2TxdcSKlmM8T8iTxO9l6XrCbvl8O5SAWT24bSXk1eyQOzeZFsBv/lp7o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=LAGOS7Am; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="LAGOS7Am" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3455D1F000E9; Wed, 20 May 2026 18:00:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779300039; bh=VNsLr4bdL7kmYc84GrfmfYxkWqA1liGAjYs6GcUR4JY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LAGOS7AmXlKCN9XTIWmGecWzIW1+h1HfuLVUadcbbEJ8bkiDXujQd0FlMOVedzr5d jAjksyHOcFZ/eRxSI04Nmpgy43WaBCqS/t40MwDFwVwgM9qU2B6pl2bRrUBYgrfiwe 4n+zzZYPBePcv6boypA6/o1j4W/OYMpcY4aCCqL4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Gui-Dong Han , Vineeth Vijayan , Danilo Krummrich , Sasha Levin Subject: [PATCH 6.12 024/666] s390/cio: use generic driver_override infrastructure Date: Wed, 20 May 2026 18:13:55 +0200 Message-ID: <20260520162111.758178348@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162111.222830634@linuxfoundation.org> References: <20260520162111.222830634@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Danilo Krummrich [ Upstream commit ac4d8bb6e2e13e8684a76ea48d13ebaaaf5c24c4 ] 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=220789 Fixes: ebc3d1791503 ("s390/cio: introduce driver_override on the css bus") Reviewed-by: Vineeth Vijayan Link: https://patch.msgid.link/20260324005919.2408620-10-dakr@kernel.org Signed-off-by: Danilo Krummrich Signed-off-by: Sasha Levin --- 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 a9057a5b670a6..23374604c6b01 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))); DECLARE_PER_CPU_ALIGNED(struct irb, cio_irb); diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index 61be7c0550bc4..b0ddbad1ebf37 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -160,7 +160,6 @@ static void css_subchannel_release(struct device *dev) sch->config.intparm = 0; cio_commit_config(sch); - kfree(sch->driver_override); kfree(sch); } @@ -324,37 +323,9 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, static DEVICE_ATTR_RO(modalias); -static ssize_t driver_override_store(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) -{ - struct subchannel *sch = to_subchannel(dev); - int ret; - - ret = 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 = to_subchannel(dev); - ssize_t len; - - device_lock(dev); - len = sysfs_emit(buf, "%s\n", sch->driver_override); - device_unlock(dev); - return len; -} -static DEVICE_ATTR_RW(driver_override); - static struct attribute *subch_attrs[] = { &dev_attr_type.attr, &dev_attr_modalias.attr, - &dev_attr_driver_override.attr, NULL, }; @@ -1358,9 +1329,11 @@ static int css_bus_match(struct device *dev, const struct device_driver *drv) struct subchannel *sch = to_subchannel(dev); const struct css_driver *driver = to_cssdriver(drv); struct css_device_id *id; + int ret; /* When driver_override is set, only bind to the matching driver */ - if (sch->driver_override && strcmp(sch->driver_override, drv->name)) + ret = device_match_driver_override(dev, drv); + if (ret == 0) return 0; for (id = driver->subchannel_type; id->match_flags; id++) { @@ -1417,6 +1390,7 @@ static int css_uevent(const struct device *dev, struct kobj_uevent_env *env) static const struct bus_type css_bus_type = { .name = "css", + .driver_override = true, .match = css_bus_match, .probe = css_probe, .remove = css_remove, -- 2.53.0