This is a note to let you know that I've just added the patch titled
usbip: add sysfs_lock to synchronize sysfs code paths
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usbip-add-sysfs_lock-to-synchronize-sysfs-code-paths.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Apr 20 01:51:40 PM CEST 2021
From: Tom Seewald <tseewald@xxxxxxxxx>
Date: Fri, 16 Apr 2021 15:53:16 -0500
Subject: usbip: add sysfs_lock to synchronize sysfs code paths
To: stable@xxxxxxxxxxxxxxx
Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>, syzbot+a93fba6d384346a761e3@xxxxxxxxxxxxxxxxxxxxxxxxx, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>, Tom Seewald <tseewald@xxxxxxxxx>, Valentina Manea <valentina.manea.m@xxxxxxxxx>, Shuah Khan <shuah@xxxxxxxxxx>
Message-ID: <20210416205319.14075-1-tseewald@xxxxxxxxx>
From: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
commit 4e9c93af7279b059faf5bb1897ee90512b258a12 upstream.
Fuzzing uncovered race condition between sysfs code paths in usbip
drivers. Device connect/disconnect code paths initiated through
sysfs interface are prone to races if disconnect happens during
connect and vice versa.
This problem is common to all drivers while it can be reproduced easily
in vhci_hcd. Add a sysfs_lock to usbip_device struct to protect the paths.
Use this in vhci_hcd to protect sysfs paths. For a complete fix, usip_host
and usip-vudc drivers and the event handler will have to use this lock to
protect the paths. These changes will be done in subsequent patches.
Cc: stable@xxxxxxxxxxxxxxx # 4.9.x
Reported-and-tested-by: syzbot+a93fba6d384346a761e3@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/b6568f7beae702bbc236a545d3c020106ca75eac.1616807117.git.skhan@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Tom Seewald <tseewald@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/usbip/usbip_common.h | 3 +++
drivers/usb/usbip/vhci_hcd.c | 1 +
drivers/usb/usbip/vhci_sysfs.c | 30 +++++++++++++++++++++++++-----
3 files changed, 29 insertions(+), 5 deletions(-)
--- a/drivers/usb/usbip/usbip_common.h
+++ b/drivers/usb/usbip/usbip_common.h
@@ -278,6 +278,9 @@ struct usbip_device {
/* lock for status */
spinlock_t lock;
+ /* mutex for synchronizing sysfs store paths */
+ struct mutex sysfs_lock;
+
int sockfd;
struct socket *tcp_socket;
--- a/drivers/usb/usbip/vhci_hcd.c
+++ b/drivers/usb/usbip/vhci_hcd.c
@@ -907,6 +907,7 @@ static void vhci_device_init(struct vhci
vdev->ud.side = USBIP_VHCI;
vdev->ud.status = VDEV_ST_NULL;
spin_lock_init(&vdev->ud.lock);
+ mutex_init(&vdev->ud.sysfs_lock);
INIT_LIST_HEAD(&vdev->priv_rx);
INIT_LIST_HEAD(&vdev->priv_tx);
--- a/drivers/usb/usbip/vhci_sysfs.c
+++ b/drivers/usb/usbip/vhci_sysfs.c
@@ -161,6 +161,8 @@ static int vhci_port_disconnect(struct v
usbip_dbg_vhci_sysfs("enter\n");
+ mutex_lock(&vdev->ud.sysfs_lock);
+
/* lock */
spin_lock_irqsave(&vhci->lock, flags);
spin_lock(&vdev->ud.lock);
@@ -171,6 +173,7 @@ static int vhci_port_disconnect(struct v
/* unlock */
spin_unlock(&vdev->ud.lock);
spin_unlock_irqrestore(&vhci->lock, flags);
+ mutex_unlock(&vdev->ud.sysfs_lock);
return -EINVAL;
}
@@ -181,6 +184,8 @@ static int vhci_port_disconnect(struct v
usbip_event_add(&vdev->ud, VDEV_EVENT_DOWN);
+ mutex_unlock(&vdev->ud.sysfs_lock);
+
return 0;
}
@@ -309,30 +314,36 @@ static ssize_t store_attach(struct devic
vhci = hcd_to_vhci(hcd);
vdev = &vhci->vdev[rhport];
+ mutex_lock(&vdev->ud.sysfs_lock);
+
/* Extract socket from fd. */
socket = sockfd_lookup(sockfd, &err);
if (!socket) {
dev_err(dev, "failed to lookup sock");
- return -EINVAL;
+ err = -EINVAL;
+ goto unlock_mutex;
}
if (socket->type != SOCK_STREAM) {
dev_err(dev, "Expecting SOCK_STREAM - found %d",
socket->type);
sockfd_put(socket);
- return -EINVAL;
+ err = -EINVAL;
+ goto unlock_mutex;
}
/* create threads before locking */
tcp_rx = kthread_create(vhci_rx_loop, &vdev->ud, "vhci_rx");
if (IS_ERR(tcp_rx)) {
sockfd_put(socket);
- return -EINVAL;
+ err = -EINVAL;
+ goto unlock_mutex;
}
tcp_tx = kthread_create(vhci_tx_loop, &vdev->ud, "vhci_tx");
if (IS_ERR(tcp_tx)) {
kthread_stop(tcp_rx);
sockfd_put(socket);
- return -EINVAL;
+ err = -EINVAL;
+ goto unlock_mutex;
}
/* get task structs now */
@@ -353,7 +364,8 @@ static ssize_t store_attach(struct devic
kthread_stop_put(tcp_tx);
dev_err(dev, "port %d already used\n", rhport);
- return -EINVAL;
+ err = -EINVAL;
+ goto unlock_mutex;
}
dev_info(dev, "pdev(%u) rhport(%u) sockfd(%d)\n",
@@ -378,7 +390,15 @@ static ssize_t store_attach(struct devic
rh_port_connect(vdev, speed);
+ dev_info(dev, "Device attached\n");
+
+ mutex_unlock(&vdev->ud.sysfs_lock);
+
return count;
+
+unlock_mutex:
+ mutex_unlock(&vdev->ud.sysfs_lock);
+ return err;
}
static DEVICE_ATTR(attach, S_IWUSR, NULL, store_attach);
Patches currently in stable-queue which might be from tseewald@xxxxxxxxx are
queue-4.9/usbip-vudc-synchronize-sysfs-code-paths.patch
queue-4.9/usbip-fix-incorrect-double-assignment-to-udc-ud.tcp_rx.patch
queue-4.9/usbip-synchronize-event-handler-with-sysfs-code-paths.patch
queue-4.9/usbip-add-sysfs_lock-to-synchronize-sysfs-code-paths.patch
queue-4.9/usbip-stub-dev-synchronize-sysfs-code-paths.patch
