On Mon, Apr 01, 2024 at 11:42:57AM +0200, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > The patch below does not apply to the 4.19-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@xxxxxxxxxxxxxxx>. > > To reproduce the conflict and resubmit, you may use the following commands: > > git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y > git checkout FETCH_HEAD > git cherry-pick -x 80ba43e9f799cbdd83842fc27db667289b3150f5 > # <resolve conflicts, build, test, etc.> > git commit -s > git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2024040157-entrench-clicker-d3df@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^.. > > Possible dependencies: > > 80ba43e9f799 ("USB: core: Fix deadlock in usb_deauthorize_interface()") > > thanks, > > greg k-h Here is the back-ported version of the patch. It was necessary to change kstrtobool to strtobool. This should apply to the -stable kernels from 4.19 up to 6.1. Alan Stern ----------------------------------------------- >From 80ba43e9f799cbdd83842fc27db667289b3150f5 Mon Sep 17 00:00:00 2001 From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Date: Tue, 12 Mar 2024 11:48:23 -0400 Subject: [PATCH] USB: core: Fix deadlock in usb_deauthorize_interface() Among the attribute file callback routines in drivers/usb/core/sysfs.c, the interface_authorized_store() function is the only one which acquires a device lock on an ancestor device: It calls usb_deauthorize_interface(), which locks the interface's parent USB device. The will lead to deadlock if another process already owns that lock and tries to remove the interface, whether through a configuration change or because the device has been disconnected. As part of the removal procedure, device_del() waits for all ongoing sysfs attribute callbacks to complete. But usb_deauthorize_interface() can't complete until the device lock has been released, and the lock won't be released until the removal has finished. The mechanism provided by sysfs to prevent this kind of deadlock is to use the sysfs_break_active_protection() function, which tells sysfs not to wait for the attribute callback. Reported-and-tested by: Yue Sun <samsun1006219@xxxxxxxxx> Reported by: xingwei lee <xrivendell7@xxxxxxxxx> Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Link: https://lore.kernel.org/linux-usb/CAEkJfYO6jRVC8Tfrd_R=cjO0hguhrV31fDPrLrNOOHocDkPoAA@xxxxxxxxxxxxxx/#r Fixes: 310d2b4124c0 ("usb: interface authorization: SysFS part of USB interface authorization") Cc: stable@xxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/1c37eea1-9f56-4534-b9d8-b443438dc869@xxxxxxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c index f98263e21c2a..d83231d6736a 100644 --- a/drivers/usb/core/sysfs.c +++ b/drivers/usb/core/sysfs.c @@ -1217,14 +1217,24 @@ static ssize_t interface_authorized_store(struct device *dev, { struct usb_interface *intf = to_usb_interface(dev); bool val; + struct kernfs_node *kn; if (strtobool(buf, &val) != 0) return -EINVAL; - if (val) + if (val) { usb_authorize_interface(intf); - else - usb_deauthorize_interface(intf); + } else { + /* + * Prevent deadlock if another process is concurrently + * trying to unregister intf. + */ + kn = sysfs_break_active_protection(&dev->kobj, &attr->attr); + if (kn) { + usb_deauthorize_interface(intf); + sysfs_unbreak_active_protection(kn); + } + } return count; }
