From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+8ab6f1042021b4eed062@syzkaller.appspotmail.com, Ilya Dryomov , "Yan, Zheng" , Sasha Levin Subject: [PATCH 4.18 074/168] ceph: avoid a use-after-free in ceph_destroy_options() Date: Mon, 8 Oct 2018 20:30:54 +0200 Message-Id: <20181008175622.886820917@linuxfoundation.org> In-Reply-To: <20181008175620.043587728@linuxfoundation.org> References: <20181008175620.043587728@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ilya Dryomov [ Upstream commit 8aaff15168cfbc7c8980fdb0e8a585f1afe56ec0 ] syzbot reported a use-after-free in ceph_destroy_options(), called from ceph_mount(). The problem was that create_fs_client() consumed the opt pointer on some errors, but not on all of them. Make sure it always consumes both libceph and ceph options. Reported-by: syzbot+8ab6f1042021b4eed062@syzkaller.appspotmail.com Signed-off-by: Ilya Dryomov Reviewed-by: "Yan, Zheng" Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/ceph/super.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) --- a/fs/ceph/super.c +++ b/fs/ceph/super.c @@ -603,6 +603,8 @@ static int extra_mon_dispatch(struct cep /* * create a new fs client + * + * Success or not, this function consumes @fsopt and @opt. */ static struct ceph_fs_client *create_fs_client(struct ceph_mount_options *fsopt, struct ceph_options *opt) @@ -610,17 +612,20 @@ static struct ceph_fs_client *create_fs_ struct ceph_fs_client *fsc; int page_count; size_t size; - int err = -ENOMEM; + int err; fsc = kzalloc(sizeof(*fsc), GFP_KERNEL); - if (!fsc) - return ERR_PTR(-ENOMEM); + if (!fsc) { + err = -ENOMEM; + goto fail; + } fsc->client = ceph_create_client(opt, fsc); if (IS_ERR(fsc->client)) { err = PTR_ERR(fsc->client); goto fail; } + opt = NULL; /* fsc->client now owns this */ fsc->client->extra_mon_dispatch = extra_mon_dispatch; fsc->client->osdc.abort_on_full = true; @@ -678,6 +683,9 @@ fail_client: ceph_destroy_client(fsc->client); fail: kfree(fsc); + if (opt) + ceph_destroy_options(opt); + destroy_mount_options(fsopt); return ERR_PTR(err); } @@ -1042,8 +1050,6 @@ static struct dentry *ceph_mount(struct fsc = create_fs_client(fsopt, opt); if (IS_ERR(fsc)) { res = ERR_CAST(fsc); - destroy_mount_options(fsopt); - ceph_destroy_options(opt); goto out_final; }