From mboxrd@z Thu Jan 1 00:00:00 1970 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 93DEC19343E; Tue, 24 Mar 2026 00:59:51 +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=1774313991; cv=none; b=S37ocMiRTdmYcfL4/vV1qdi4OAbN87RSy2kG/a8n1QzcDdxukKv8f71zxk4372F/gFO8aWtXOzdwI0I5MsL96htgLTNbmFwMoIzSt8idq7FbsfGHQqnWuxxxR/eaX9HL3GsEFFqL0tjQass5JWD2GzIPWMQ8dO5SEIs86Snt49Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774313991; c=relaxed/simple; bh=8SBWPlY0FpAPUZM3VGM6jk8MBe902KSJN4WiLZGAbHc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UlUfZ0iA/ANBv0K0+84/c1p7/VQ4uL19+sxWcR3D0MKS2dYoXTW8+kyAFa6e/j+galq7T3GqDG0xPly8VBSPf1WMUAHjO/3fXEHvRJJiRoDTgCvMbtn6iaPks55+Sdcp/CZHTuWr2QBcLuLi+oO3hXKu3tWNge8mIOEv/GdvqBU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fg9y82ia; 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="fg9y82ia" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 138D4C4CEF7; Tue, 24 Mar 2026 00:59:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774313991; bh=8SBWPlY0FpAPUZM3VGM6jk8MBe902KSJN4WiLZGAbHc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fg9y82iadfDPF6nOAy0HmPYPAiOP6FG/VDHn1TkIcmsusWoR+G/nVZNnCuZY075br gKlvWvjVdGmnI0JgptoDvayEdCUtkEYfsg2A7PluZUkmjkJczc4SoAIa2b+24cTLMO ehoUBK1kyWeitGv4Js4jW16nmf/+SUVzGnTpP2KwCYTWTgtSAqvsLMsfsTs35ptcMx Qhx+u6Ww/NKX1+DPPnLU1acTql1U6mNB+wnFZugPadRV0p5Gw0gHRTgVhOLxhxmRdq AfBcD9mRlS2Zl/SNmQhvetfwNouTevadSCvwGk1WKIFaHCmyoKhqRcaFynIdgVlqMc HA/jQLBEPF5WA== 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 02/12] bus: fsl-mc: use generic driver_override infrastructure Date: Tue, 24 Mar 2026 01:59:06 +0100 Message-ID: <20260324005919.2408620-3-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: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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: 1f86a00c1159 ("bus/fsl-mc: add support for 'driver_override' in the mc-bus") Signed-off-by: Danilo Krummrich --- drivers/bus/fsl-mc/fsl-mc-bus.c | 43 +++++-------------------------- drivers/vfio/fsl-mc/vfio_fsl_mc.c | 4 +-- include/linux/fsl/mc.h | 4 --- 3 files changed, 8 insertions(+), 43 deletions(-) diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c index c117745cf206..221146e4860b 100644 --- a/drivers/bus/fsl-mc/fsl-mc-bus.c +++ b/drivers/bus/fsl-mc/fsl-mc-bus.c @@ -86,12 +86,16 @@ static int fsl_mc_bus_match(struct device *dev, const struct device_driver *drv) struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev); const struct fsl_mc_driver *mc_drv = to_fsl_mc_driver(drv); bool found = false; + int ret; /* When driver_override is set, only bind to the matching driver */ - if (mc_dev->driver_override) { - found = !strcmp(mc_dev->driver_override, mc_drv->driver.name); + ret = device_match_driver_override(dev, drv); + if (ret > 0) { + found = true; goto out; } + if (ret == 0) + goto out; if (!mc_drv->match_id_table) goto out; @@ -210,39 +214,8 @@ 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 fsl_mc_device *mc_dev = to_fsl_mc_device(dev); - int ret; - - if (WARN_ON(dev->bus != &fsl_mc_bus_type)) - return -EINVAL; - - ret = driver_set_override(dev, &mc_dev->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 fsl_mc_device *mc_dev = to_fsl_mc_device(dev); - ssize_t len; - - device_lock(dev); - len = sysfs_emit(buf, "%s\n", mc_dev->driver_override); - device_unlock(dev); - return len; -} -static DEVICE_ATTR_RW(driver_override); - static struct attribute *fsl_mc_dev_attrs[] = { &dev_attr_modalias.attr, - &dev_attr_driver_override.attr, NULL, }; @@ -345,6 +318,7 @@ ATTRIBUTE_GROUPS(fsl_mc_bus); const struct bus_type fsl_mc_bus_type = { .name = "fsl-mc", + .driver_override = true, .match = fsl_mc_bus_match, .uevent = fsl_mc_bus_uevent, .probe = fsl_mc_probe, @@ -910,9 +884,6 @@ static struct notifier_block fsl_mc_nb; */ void fsl_mc_device_remove(struct fsl_mc_device *mc_dev) { - kfree(mc_dev->driver_override); - mc_dev->driver_override = NULL; - /* * The device-specific remove callback will get invoked by device_del() */ diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c index 462fae1aa538..b4c3958201b2 100644 --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c @@ -424,9 +424,7 @@ static int vfio_fsl_mc_bus_notifier(struct notifier_block *nb, if (action == BUS_NOTIFY_ADD_DEVICE && vdev->mc_dev == mc_cont) { - mc_dev->driver_override = kasprintf(GFP_KERNEL, "%s", - vfio_fsl_mc_ops.name); - if (!mc_dev->driver_override) + if (device_set_driver_override(dev, vfio_fsl_mc_ops.name)) dev_warn(dev, "VFIO_FSL_MC: Setting driver override for device in dprc %s failed\n", dev_name(&mc_cont->dev)); else diff --git a/include/linux/fsl/mc.h b/include/linux/fsl/mc.h index 897d6211c163..1da63f2d7040 100644 --- a/include/linux/fsl/mc.h +++ b/include/linux/fsl/mc.h @@ -178,9 +178,6 @@ struct fsl_mc_obj_desc { * @regions: pointer to array of MMIO region entries * @irqs: pointer to array of pointers to interrupts allocated to this device * @resource: generic resource associated with this MC object device, if any. - * @driver_override: driver name to force a match; do not set directly, - * because core frees it; use driver_set_override() to - * set or clear it. * * Generic device object for MC object devices that are "attached" to a * MC bus. @@ -214,7 +211,6 @@ struct fsl_mc_device { struct fsl_mc_device_irq **irqs; struct fsl_mc_resource *resource; struct device_link *consumer_link; - const char *driver_override; }; #define to_fsl_mc_device(_dev) \ -- 2.53.0