Commit dbe53402 authored Dec 30, 2016 by Eric Biggers Committed by Amit Pundir Jan 16, 2017

net: socket: don't set sk_uid to garbage value in ->setattr()



->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.

[backport of net e1a3a60a2ebe991605acb14cd58e39c0545e174e]

Bug: 16355602
Change-Id: I20e53848e54282b72a388ce12bfa88da5e3e9efe
Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Tested-by: Lorenzo Colitti <lorenzo@google.com>
Acked-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent e72b75ee

net/socket.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -528,7 +528,7 @@ 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(dentry->d_inode);

		sock->sk->sk_uid = iattr->ia_uid;