From: Antonio Ospite <ospite@studenti.unina.it>
Date: Tue, 5 Oct 2010 15:20:16 +0000 (+0200)
Subject: HID: hidraw, fix a NULL pointer dereference in hidraw_ioctl
X-Git-Tag: v2.6.34.9~108
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=24977195f50960222eb9ad2982e6cd252ff9f63f;p=thirdparty%2Fkernel%2Fstable.git

HID: hidraw, fix a NULL pointer dereference in hidraw_ioctl

commit d20d5ffab92f00188f360c44c791a5ffb988247c upstream.

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.

[PG: slightly/trivially reworked for backport to 34]

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 6eadf1a9b3cca..0db1a0f5d2a0d 100644
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -243,6 +243,11 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,
 	void __user *user_arg = (void __user*) arg;
 
 	lock_kernel();
+	if (!dev) {
+		ret = -ENODEV;
+		goto out;
+	}
+
 	switch (cmd) {
 		case HIDIOCGRDESCSIZE:
 			if (put_user(dev->hid->rsize, (int __user *)arg))
@@ -315,6 +320,7 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,
 
 		ret = -ENOTTY;
 	}
+out:
 	unlock_kernel();
 	return ret;
 }