From 0c212370ff815a4263bf80bba5dace7eea913bda Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Tue, 31 Jan 2023 15:49:04 -0500 Subject: USB: core: Don't hold device lock while reading the "descriptors" sysfs file commit 45bf39f8df7f05efb83b302c65ae3b9bc92b7065 upstream. Ever since commit 83e83ecb79a8 ("usb: core: get config and string descriptors for unauthorized devices") was merged in 2013, there has been no mechanism for reallocating the rawdescriptors buffers in struct usb_device after the initial enumeration. Before that commit, the buffers would be deallocated when a device was deauthorized and reallocated when it was authorized and enumerated. This means that the locking in the read_descriptors() routine is not needed, since the buffers it reads will never be reallocated while the routine is running. This locking can interfere with user programs trying to read a hub's descriptors via sysfs while new child devices of the hub are being initialized, since the hub is locked during this procedure. Since the locking in read_descriptors() hasn't been needed for over nine years, we can remove it. Reported-and-tested-by: Troels Liebe Bentsen Change-Id: Ib38603b37746e8e3e22e2b4fd3040278ee391feb Signed-off-by: Alan Stern CC: stable@vger.kernel.org Link: https://lore.kernel.org/r/Y9l+wDTRbuZABzsE@rowland.harvard.edu Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ulrich Hecht AG: Squash with "USB: core: remove device lock left behind by mismerge" --- drivers/usb/core/hub.c | 5 ++--- drivers/usb/core/sysfs.c | 2 -- 2 files changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index afd509564e2e..d2fb62380b50 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2257,9 +2257,8 @@ static int usb_enumerate_device_otg(struct usb_device *udev) * usb_enumerate_device - Read device configs/intfs/otg (usbcore-internal) * @udev: newly addressed device (in ADDRESS state) * - * This is only called by usb_new_device() and usb_authorize_device() - * and FIXME -- all comments that apply to them apply here wrt to - * environment. + * This is only called by usb_new_device() -- all comments that apply there + * apply here wrt to environment. * * If the device is WUSB and not authorized, we don't attempt to read * the string descriptors, as they will be errored out by the device diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c index 6dc0f4e25cf3..c7c32326d50c 100644 --- a/drivers/usb/core/sysfs.c +++ b/drivers/usb/core/sysfs.c @@ -825,7 +825,6 @@ read_descriptors(struct file *filp, struct kobject *kobj, * Following that are the raw descriptor entries for all the * configurations (config plus subsidiary descriptors). */ - usb_lock_device(udev); for (cfgno = -1; cfgno < udev->descriptor.bNumConfigurations && nleft > 0; ++cfgno) { if (cfgno < 0) { @@ -846,7 +845,6 @@ read_descriptors(struct file *filp, struct kobject *kobj, off -= srclen; } } - usb_unlock_device(udev); return count - nleft; } -- cgit v1.2.3