This is a note to let you know that I've just added the patch titled usbip: synchronize event handler with 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-synchronize-event-handler-with-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 15:53:19 -0500 Subject: usbip: synchronize event handler with 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: <20210416205319.14075-4-tseewald@xxxxxxxxx> From: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> commit 363eaa3a450abb4e63bd6e3ad79d1f7a0f717814 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. Use sysfs_lock to synchronize event handler with sysfs paths in usbip drivers. 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/c5c8723d3f29dfe3d759cfaafa7dd16b0dfe2918.1616807117.git.skhan@xxxxxxxxxxxxxxxxxxx Signed-off-by: Tom Seewald <tseewald@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/usbip/usbip_event.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/usb/usbip/usbip_event.c +++ b/drivers/usb/usbip/usbip_event.c @@ -84,6 +84,7 @@ static void event_handler(struct work_st 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. @@ -104,6 +105,7 @@ static void event_handler(struct work_st ud->eh_ops.unusable(ud); unset_event(ud, USBIP_EH_UNUSABLE); } + mutex_unlock(&ud->sysfs_lock); wake_up(&ud->eh_waitq); } 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