[PATCH v4 04/12] usb: usbip: stub: serialize usbip_sockfd_store() against event_handler()
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: 2021-03-04 15:27:33
Subsystem:
the rest, usb over ip driver, usb subsystem · Maintainers:
Linus Torvalds, Valentina Manea, Shuah Khan, Greg Kroah-Hartman
usbip_sockfd_store() must perform
if (sdev->ud.status != SDEV_ST_AVAILABLE) {
/* misc assignments for attach operation */
sdev->ud.status = SDEV_ST_USED;
}
under a lock, or multiple ud->tcp_{tx,rx} are created (which will later
cause a crash like [1]) and refcount on ud->tcp_socket is leaked when
usbip_sockfd_store() is concurrently called.
Since I don't want to replace "return" with "goto" in order to call
usbip_event_unlock(), wrap whole function in order to keep changes
minimal.
[1] https://syzkaller.appspot.com/bug?extid=95ce4b142579611ef0a9
Reported-by: syzbot <redacted>
Tested-by: syzbot <redacted>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
drivers/usb/usbip/stub_dev.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/usbip/stub_dev.c b/drivers/usb/usbip/stub_dev.c
index 2305d425e6c9..cea5663d1994 100644
--- a/drivers/usb/usbip/stub_dev.c
+++ b/drivers/usb/usbip/stub_dev.c@@ -39,8 +39,8 @@ static DEVICE_ATTR_RO(usbip_status); * is used to transfer usbip requests by kernel threads. -1 is a magic number * by which usbip connection is finished. */ -static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *attr, - const char *buf, size_t count) +static ssize_t __usbip_sockfd_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) { struct stub_device *sdev = dev_get_drvdata(dev); int sockfd = 0;
@@ -104,6 +104,17 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a spin_unlock_irq(&sdev->ud.lock); return -EINVAL; } +static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + ssize_t ret = usbip_event_lock_killable(); + + if (ret) + return ret; + ret = __usbip_sockfd_store(dev, attr, buf, count); + usbip_event_unlock(); + return ret; +} static DEVICE_ATTR_WO(usbip_sockfd); static struct attribute *usbip_attrs[] = {
--
2.18.4