Commit 46b53c29 authored Mar 26, 2019 by Al Viro Committed by Greg Kroah-Hartman May 04, 2019

ceph: fix use-after-free on symlink traversal



[ Upstream commit daf5cc27eed99afdea8d96e71b89ba41f5406ef6 ]

free the symlink body after the same RCU delay we have for freeing the
struct inode itself, so that traversal during RCU pathwalk wouldn't step
into freed memory.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>

parent 8293a624

fs/ceph/inode.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -523,6 +523,7 @@ static void ceph_i_callback(struct rcu_head *head)
		struct inode *inode = container_of(head, struct inode, i_rcu);
		struct ceph_inode_info *ci = ceph_inode(inode);

		kfree(ci->i_symlink);
		kmem_cache_free(ceph_inode_cachep, ci);
		}

		@@ -554,7 +555,6 @@ void ceph_destroy_inode(struct inode *inode)
		ceph_put_snap_realm(mdsc, realm);
		}

		kfree(ci->i_symlink);
		while ((n = rb_first(&ci->i_fragtree)) != NULL) {
		frag = rb_entry(n, struct ceph_inode_frag, node);
		rb_erase(n, &ci->i_fragtree);