From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Subject: [PATCH] net: socket: don't set sk_uid to garbage value in ->setattr() Date: Fri, 30 Dec 2016 17:42:32 -0600 Message-ID: <20161230234232.4221-1-ebiggers3@gmail.com> Cc: "David S. Miller" , Lorenzo Colitti , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Eric Biggers To: netdev@vger.kernel.org Return-path: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Eric Biggers ->setattr() was recently implemented for socket files to sync the socket inode's uid to the new 'sk_uid' member of struct sock. It does this by copying over the ia_uid member of struct iattr. However, ia_uid is actually only valid when ATTR_UID is set in ia_valid, indicating that the uid is being changed, e.g. by chown. Other metadata operations such as chmod or utimes leave ia_uid uninitialized. Therefore, sk_uid could be set to a "garbage" value from the stack. Fix this by only copying the uid over when ATTR_UID is set. Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.") Signed-off-by: Eric Biggers --- net/socket.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/socket.c b/net/socket.c index 8487bf136e5c..a8c2307590b8 100644 --- a/net/socket.c +++ b/net/socket.c @@ -537,7 +537,7 @@ int sockfs_setattr(struct dentry *dentry, struct iattr *iattr) { int err = simple_setattr(dentry, iattr); - if (!err) { + if (!err && (iattr->ia_valid & ATTR_UID)) { struct socket *sock = SOCKET_I(d_inode(dentry)); sock->sk->sk_uid = iattr->ia_uid; -- 2.11.0