HID: hidraw, fix a NULL pointer dereference in hidraw_write

commit e42dee9a99a3ecd32b5c027e8f7411fb5bc11eb6 upstream.

BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
IP: [<ffffffffa0f0a625>] hidraw_write+0x3b/0x116 [hid]
[...]

This is reproducible by disconnecting the device while userspace writes
to dev node in a loop and doesn't check return values in order to exit
the loop.

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index f43e95e11d4809c7e9d8889914510d38e69a7c34..7dca2faacdfa253d512865b6edaf03a291fd1b6d 100644 (file)
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -111,6 +111,12 @@ static ssize_t hidraw_write(struct file *file, const char __user *buffer, size_t
        int ret = 0;
 
        mutex_lock(&minors_lock);
+
+       if (!hidraw_table[minor]) {
+               ret = -ENODEV;
+               goto out;
+       }
+
        dev = hidraw_table[minor]->hid;
 
        if (!dev->hid_output_raw_report) {