[PATCH 3.12 016/181] net/compat: Fix minor information leak in siocdevprivate_ioctl()

[Jiri Slaby]

From: Ben Hutchings <bhutchings@xxxxxxxxxxxxxx>

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

===============

commit 417c3522b3202dacce4873cfb0190459fbce95c5 upstream.

We don't need to check that ifr_data itself is a valid user pointer,
but we should check &ifr_data is.  Thankfully the copy of ifr_name is
checked, so this can only leak a few bytes from immediately above the
user address limit.

Signed-off-by: Ben Hutchings <bhutchings@xxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 net/socket.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/net/socket.c b/net/socket.c
index dc57dae20a9a..c8ca896a9a5a 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -3023,19 +3023,16 @@ static int siocdevprivate_ioctl(struct net *net, unsigned int cmd,
 	if (copy_from_user(&tmp_buf[0], &(u_ifreq32->ifr_ifrn.ifrn_name[0]),
 			   IFNAMSIZ))
 		return -EFAULT;
-	if (__get_user(data32, &u_ifreq32->ifr_ifru.ifru_data))
+	if (get_user(data32, &u_ifreq32->ifr_ifru.ifru_data))
 		return -EFAULT;
 	data64 = compat_ptr(data32);
 
 	u_ifreq64 = compat_alloc_user_space(sizeof(*u_ifreq64));
 
-	/* Don't check these user accesses, just let that get trapped
-	 * in the ioctl handler instead.
-	 */
 	if (copy_to_user(&u_ifreq64->ifr_ifrn.ifrn_name[0], &tmp_buf[0],
 			 IFNAMSIZ))
 		return -EFAULT;
-	if (__put_user(data64, &u_ifreq64->ifr_ifru.ifru_data))
+	if (put_user(data64, &u_ifreq64->ifr_ifru.ifru_data))
 		return -EFAULT;
 
 	return dev_ioctl(net, cmd, u_ifreq64);
-- 
2.0.0

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