HID: keep dev_rdesc unmodified and use it for comparisons

The dev_rdesc member of the hid_device structure is meant to store the original
report descriptor received from the device, but it is currently passed to any
report_fixup method before it is copied to the rdesc member. This patch uses a
temporary buffer to shield dev_rdesc from the side effects of many HID drivers'
report_fixup implementations.

usbhid's hid_post_reset checks the report descriptor currently returned by the
device against a descriptor that may have been modified by a driver's
report_fixup method. That leaves some devices nonfunctional after a resume, with
a "reset_resume error 1" reported. This patch checks the new descriptor against
the unmodified dev_rdesc instead and uses the original, instead of modified,
report size.

BugLink: http://bugs.launchpad.net/bugs/1049623
Signed-off-by: Kevin Daughtridge <kevin@kdau.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index dd679a582c2c6ad9ec9fc0e6bdb830163b21bada..ec917690c263d870d7119f0ff588d3ec7a9c0083 100644 (file)
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -757,6 +757,7 @@ int hid_open_report(struct hid_device *device)
        struct hid_item item;
        unsigned int size;
        __u8 *start;
+       __u8 *buf;
        __u8 *end;
        int ret;
        static int (*dispatch_type[])(struct hid_parser *parser,
@@ -775,12 +776,21 @@ int hid_open_report(struct hid_device *device)
                return -ENODEV;
        size = device->dev_rsize;
 
+       buf = kmemdup(start, size, GFP_KERNEL);
+       if (buf == NULL)
+               return -ENOMEM;
+
        if (device->driver->report_fixup)
-               start = device->driver->report_fixup(device, start, &size);
+               start = device->driver->report_fixup(device, buf, &size);
+       else
+               start = buf;
 
-       device->rdesc = kmemdup(start, size, GFP_KERNEL);
-       if (device->rdesc == NULL)
+       start = kmemdup(start, size, GFP_KERNEL);
+       kfree(buf);
+       if (start == NULL)
                return -ENOMEM;
+
+       device->rdesc = start;
        device->rsize = size;
 
        parser = vzalloc(sizeof(struct hid_parser));

diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index dedd8e4e5c6ddeaff6db3eb8dab01e1dffe20574..8e0c4bf94ebc44b8a3cf214bfd82b9000a7b874a 100644 (file)
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -1415,20 +1415,20 @@ static int hid_post_reset(struct usb_interface *intf)
         * configuration descriptors passed, we already know that
         * the size of the HID report descriptor has not changed.
         */
-       rdesc = kmalloc(hid->rsize, GFP_KERNEL);
+       rdesc = kmalloc(hid->dev_rsize, GFP_KERNEL);
        if (!rdesc) {
                dbg_hid("couldn't allocate rdesc memory (post_reset)\n");
                return 1;
        }
        status = hid_get_class_descriptor(dev,
                                interface->desc.bInterfaceNumber,
-                               HID_DT_REPORT, rdesc, hid->rsize);
+                               HID_DT_REPORT, rdesc, hid->dev_rsize);
        if (status < 0) {
                dbg_hid("reading report descriptor failed (post_reset)\n");
                kfree(rdesc);
                return 1;
        }
-       status = memcmp(rdesc, hid->rdesc, hid->rsize);
+       status = memcmp(rdesc, hid->dev_rdesc, hid->dev_rsize);
        kfree(rdesc);
        if (status != 0) {
                dbg_hid("report descriptor changed\n");