: Fix WEXT userland corruption on 64-bit

This bug affects WEXT usage on all 64-bit platforms, compat mode or not. It overwrites 8 bytes past the end of the userland iwreq.

I've checked the following patch into my net-2.6 tree and will queue it up for -stable too.

Shaddy, this should fix the "encryption key is too long" iwconfig issue.

I'll try to figure out why iwlist gets a bus error and the zd1211rw driver generates all of those unaligned access errors next.

commit 0a06ea87185531705e4417e3a051f81b64f210c1

Author: David S. Miller <[email protected]>
Date:   Tue Nov 20 03:29:53 2007 -0800

[WIRELESS] WEXT: Fix userspace corruption on 64-bit.

On 64-bit systems sizeof(struct ifreq) is 8 bytes larger than sizeof(struct iwreq).

For GET calls, the wireless extension code copies back into userspace using sizeof(struct ifreq) but userspace and elsewhere only allocates a "struct iwreq". Thus, this copy writes past the end of the iwreq object and corrupts whatever sits after it in memory.

Fix the copy_to_user() length.

This particularly hurts the compat case because the wireless compat code uses compat_alloc_userspace() and right after this allocated buffer is the current bottom of the user stack, and that's what gets overwritten by the copy_to_user() call.

index 85e5f9d..47e80cc 100644
@@ -1094,7 +1094,7 @@ int wext_handle_ioctl(struct net *net, struct ifreq *ifr, unsigned int cmd,
 	rtnl_lock();
 	ret = wireless_process_ioctl(net, ifr, cmd);
 	rtnl_unlock();
-	if (IW_IS_GET(cmd) && copy_to_user(arg, ifr, sizeof(struct ifreq)))
+	if (IW_IS_GET(cmd) && copy_to_user(arg, ifr, sizeof(struct iwreq)))
 		return -EFAULT;
 	return ret;
 }