linux-kernel - [PATCH] wireless: wext: terminate ifr name coming from userspace

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Date:   Tue, 18 Jul 2017 04:23:16 +0000
From:   "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
To:     "johannes.berg@...el.com" <johannes.berg@...el.com>,
        "davem@...emloft.net" <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
Subject: [PATCH] wireless: wext: terminate ifr name coming from userspace

ifr name is assumed to be a valid string by the kernel, but nothing
was forcing username to pass a valid string.

In turn, this would cause panics as we tried to access the string
past it's valid memory.

Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 net/core/dev_ioctl.c   | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

index 82fd4c9c4a1b..7657ad6bc13d 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -424,6 +424,8 @@ int dev_ioctl(struct net *net, unsigned int cmd, void __user *arg)
 		if (copy_from_user(&iwr, arg, sizeof(iwr)))
 			return -EFAULT;
 
+		iwr.ifr_name[sizeof(iwr.ifr_name) - 1] = 0;
+
 		return wext_handle_ioctl(net, &iwr, cmd, arg);
 	}
 
-- 
2.11.0