The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 363eaa3a450abb4e63bd6e3ad79d1f7a0f717814 Mon Sep 17 00:00:00 2001
From: Shuah Khan skhan@linuxfoundation.org Date: Mon, 29 Mar 2021 19:36:51 -0600 Subject: [PATCH] usbip: synchronize event handler with sysfs code paths
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 synchronize event handler with sysfs paths in usbip drivers.
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/c5c8723d3f29dfe3d759cfaafa7dd16b0dfe2918.161680711... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
diff --git a/drivers/usb/usbip/usbip_event.c b/drivers/usb/usbip/usbip_event.c index 5d88917c9631..086ca76dd053 100644 --- a/drivers/usb/usbip/usbip_event.c +++ b/drivers/usb/usbip/usbip_event.c @@ -70,6 +70,7 @@ static void event_handler(struct work_struct *work) while ((ud = get_event()) != NULL) { usbip_dbg_eh("pending event %lx\n", ud->event);
+ mutex_lock(&ud->sysfs_lock); /* * NOTE: shutdown must come first. * Shutdown the device. @@ -90,6 +91,7 @@ static void event_handler(struct work_struct *work) ud->eh_ops.unusable(ud); unset_event(ud, USBIP_EH_UNUSABLE); } + mutex_unlock(&ud->sysfs_lock);
wake_up(&ud->eh_waitq); }