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authorAlan Stern <stern@rowland.harvard.edu>2023-01-31 23:49:04 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-03-03 13:52:25 +0300
commitc87fb861ec185fdc578b4fdc6a05920b6a843840 (patch)
treedebc0e879b58420add6502f0e6d09b4c5b5602ed /drivers
parentc49bd6c2dd1bd67abd2b638ae10deb65c4f4031e (diff)
downloadlinux-c87fb861ec185fdc578b4fdc6a05920b6a843840.tar.xz
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 <troels@connectedcars.dk> Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: stable@vger.kernel.org Link: https://lore.kernel.org/r/Y9l+wDTRbuZABzsE@rowland.harvard.edu Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/usb/core/hub.c5
-rw-r--r--drivers/usb/core/sysfs.c5
2 files changed, 2 insertions, 8 deletions
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 0aaaadb02cc6..1abe43ddb75f 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2389,9 +2389,8 @@ 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 631574718d8a..ccf6cd972269 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -868,11 +868,7 @@ read_descriptors(struct file *filp, struct kobject *kobj,
size_t srclen, n;
int cfgno;
void *src;
- int retval;
- retval = usb_lock_device_interruptible(udev);
- if (retval < 0)
- return -EINTR;
/* The binary attribute begins with the device descriptor.
* Following that are the raw descriptor entries for all the
* configurations (config plus subsidiary descriptors).
@@ -897,7 +893,6 @@ read_descriptors(struct file *filp, struct kobject *kobj,
off -= srclen;
}
}
- usb_unlock_device(udev);
return count - nleft;
}