From 9dbf34a834563dada91366c2ac266f32ff34641a Mon Sep 17 00:00:00 2001
From: Shuah Khan <skhan@linuxfoundation.org>
Date: Mon, 29 Mar 2021 19:36:49 -0600
Subject: [PATCH] usbip: stub-dev synchronize sysfs code paths
Git-commit: 9dbf34a834563dada91366c2ac266f32ff34641a
References: git-fixes
Patch-mainline: v5.12-rc7
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.
Use sysfs_lock to protect sysfs paths in stub-dev.
Cc: stable@vger.kernel.org
Reported-and-tested-by: syzbot+a93fba6d384346a761e3@syzkaller.appspotmail.com
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/2b182f3561b4a065bf3bf6dce3b0e9944ba17b3f.1616807117.git.skhan@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/usb/usbip/stub_dev.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/drivers/usb/usbip/stub_dev.c
+++ b/drivers/usb/usbip/stub_dev.c
@@ -77,6 +77,7 @@ static ssize_t usbip_sockfd_store(struct
dev_info(dev, "stub up\n");
+ mutex_lock(&sdev->ud.sysfs_lock);
spin_lock_irq(&sdev->ud.lock);
if (sdev->ud.status != SDEV_ST_AVAILABLE) {
@@ -101,13 +102,13 @@ static ssize_t usbip_sockfd_store(struct
tcp_rx = kthread_create(stub_rx_loop, &sdev->ud, "stub_rx");
if (IS_ERR(tcp_rx)) {
sockfd_put(socket);
- return -EINVAL;
+ goto unlock_mutex;
}
tcp_tx = kthread_create(stub_tx_loop, &sdev->ud, "stub_tx");
if (IS_ERR(tcp_tx)) {
kthread_stop(tcp_rx);
sockfd_put(socket);
- return -EINVAL;
+ goto unlock_mutex;
}
/* get task structs now */
@@ -126,6 +127,8 @@ static ssize_t usbip_sockfd_store(struct
wake_up_process(sdev->ud.tcp_rx);
wake_up_process(sdev->ud.tcp_tx);
+ mutex_unlock(&sdev->ud.sysfs_lock);
+
} else {
dev_info(dev, "stub down\n");
@@ -136,6 +139,7 @@ static ssize_t usbip_sockfd_store(struct
spin_unlock_irq(&sdev->ud.lock);
usbip_event_add(&sdev->ud, SDEV_EVENT_DOWN);
+ mutex_unlock(&sdev->ud.sysfs_lock);
}
return count;
@@ -144,6 +148,8 @@ sock_err:
sockfd_put(socket);
err:
spin_unlock_irq(&sdev->ud.lock);
+unlock_mutex:
+ mutex_unlock(&sdev->ud.sysfs_lock);
return -EINVAL;
}
static DEVICE_ATTR_WO(usbip_sockfd);
@@ -309,6 +315,7 @@ static struct stub_device *stub_device_a
sdev->ud.side = USBIP_STUB;
sdev->ud.status = SDEV_ST_AVAILABLE;
spin_lock_init(&sdev->ud.lock);
+ mutex_init(&sdev->ud.sysfs_lock);
sdev->ud.tcp_socket = NULL;
sdev->ud.sockfd = -1;