HID: hidraw, fix a NULL pointer dereference in hidraw_ioctl

BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
IP: [<ffffffffa02c66b4>] hidraw_ioctl+0xfc/0x32c [hid]
[...]

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

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Cc: stable@kernel.org
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 47d70c523d9..9eaf6ae5f97 100644
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -244,6 +244,10 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,
 
         mutex_lock(&minors_lock);
         dev = hidraw_table[minor];
+        if (!dev) {
+                ret = -ENODEV;
+                goto out;
+        }
 
         switch (cmd) {
                 case HIDIOCGRDESCSIZE:
@@ -317,6 +321,7 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,
 
                 ret = -ENOTTY;
         }
+out:
         mutex_unlock(&minors_lock);
         return ret;
 }