linux-kernel - [ 094/109] net/tun: fix ioctl() based info leaks

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Message-Id: <20120807222051.335989141@linuxfoundation.org>
Date:	Tue,  7 Aug 2012 15:35:53 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Mathias Krause <minipli@...glemail.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 094/109] net/tun: fix ioctl() based info leaks

From: Greg KH <gregkh@...uxfoundation.org>

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Mathias Krause <minipli@...glemail.com>

[ Upstream commits a117dacde0288f3ec60b6e5bcedae8fa37ee0dfc
  and 8bbb181308bc348e02bfdbebdedd4e4ec9d452ce ]

The tun module leaks up to 36 bytes of memory by not fully initializing
a structure located on the stack that gets copied to user memory by the
TUNGETIFF and SIOCGIFHWADDR ioctl()s.

Signed-off-by: Mathias Krause <minipli@...glemail.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/tun.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1255,10 +1255,12 @@ static long __tun_chr_ioctl(struct file
 	int vnet_hdr_sz;
 	int ret;
 
-	if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89)
+	if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89) {
 		if (copy_from_user(&ifr, argp, ifreq_len))
 			return -EFAULT;
-
+	} else {
+		memset(&ifr, 0, sizeof(ifr));
+	}
 	if (cmd == TUNGETFEATURES) {
 		/* Currently this just means: "what IFF flags are valid?".
 		 * This is needed because we never checked for invalid flags on


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