[v2.6.34-stable 059/213] net/tun: fix ioctl() based info leaks

[Paul Gortmaker]

From: Mathias Krause <minipli@xxxxxxxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit a117dacde0288f3ec60b6e5bcedae8fa37ee0dfc upstream.

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@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 drivers/net/tun.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 7b4a88b2f696..c777d8ebdaa8 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1177,9 +1177,11 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
 	int sndbuf;
 	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?".
-- 
1.8.5.2

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