[ 116/180] net/tun: fix ioctl() based info leaks

[Willy Tarreau]

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

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

From: Mathias Krause <minipli@xxxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
---
 drivers/net/tun.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 0f77aca..894ad84 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1121,10 +1121,12 @@ 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, sizeof ifr))
 			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
-- 
1.7.2.1.45.g54fbc



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