[PATCH 3.16 125/366] HID: hidraw: Fix crash on HIDIOCGFEATURE with a destroyed device

Ben Hutchings
2018-10-14T23:27:53Z

From: Rodrigo Rivas Costa <rodrigorivascosta@gmail.com>

commit a955358d54695e4ad9f7d6489a7ac4d69a8fc711 upstream.

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.

Signed-off-by: Rodrigo Rivas Costa <rodrigorivascosta@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/hid/hidraw.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -197,6 +197,11 @@ static ssize_t hidraw_get_report(struct
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) {