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    Subject[PATCH 5.0 074/101] ceph: fix use-after-free on symlink traversal
    Date
    [ 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>
    ---
    fs/ceph/inode.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
    index 9d1f34d46627..f7f9e305aaf8 100644
    --- a/fs/ceph/inode.c
    +++ b/fs/ceph/inode.c
    @@ -524,6 +524,7 @@ 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);
    }

    @@ -561,7 +562,6 @@ 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);
    --
    2.19.1


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