HID: hidraw: Fix crash on HIDIOCGFEATURE with a destroyed device

Doing `ioctl(HIDIOCGFEATURE)` in a tight loop on a hidraw device
and then disconnecting the device, or unloading the driver, can
cause a NULL pointer dereference.

When a hidraw device is destroyed it sets 0 to `dev->exist`.
Most functions check 'dev->exist' before doing its work, but
`hidraw_get_report()` was missing that check.

Cc: stable@vger.kernel.org
Signed-off-by: Rodrigo Rivas Costa <rodrigorivascosta@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index fbfcc80094329e561c7dfaa0fd3e411144503a49..b39844adea47a333f52079abbefa2ee0186bb13b 100644 (file)
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -192,6 +192,11 @@ static ssize_t hidraw_get_report(struct file *file, char __user *buffer, size_t
        int ret = 0, len;
        unsigned char report_number;
 
+       if (!hidraw_table[minor] || !hidraw_table[minor]->exist) {
+               ret = -ENODEV;
+               goto out;
+       }
+
        dev = hidraw_table[minor]->hid;
 
        if (!dev->ll_driver->raw_request) {