[Ocfs2-devel] [PATCH] ocfs2: Fix locking for res->tracking and dlm->tracking_list
Joseph Qi
jiangqi903 at gmail.com
Fri Jun 22 01:32:40 PDT 2018
On 18/6/22 07:57, Ashish Samant wrote:
> In dlm_init_lockres() and dlm_unregister_domain() we access and modify
> res->tracking and dlm->tracking_list without holding dlm->track_lock.
> This can cause list corruptions and can end up in kernel panic.
>
> Fix this by locking res->tracking and dlm->tracking_list with
> dlm->track_lock at all places.
>
> Signed-off-by: Ashish Samant <ashish.samant at oracle.com>
> ---
> fs/ocfs2/dlm/dlmdomain.c | 2 ++
> fs/ocfs2/dlm/dlmmaster.c | 4 ++--
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
> index 2acd58b..cfb1edd 100644
> --- a/fs/ocfs2/dlm/dlmdomain.c
> +++ b/fs/ocfs2/dlm/dlmdomain.c
> @@ -723,6 +723,7 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm)
> mlog(0, "%s: more migration to do\n", dlm->name);
> }
>
> + spin_lock(&dlm->track_lock);
> /* This list should be empty. If not, print remaining lockres */
> if (!list_empty(&dlm->tracking_list)) {
> mlog(ML_ERROR, "Following lockres' are still on the "
> @@ -730,6 +731,7 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm)
> list_for_each_entry(res, &dlm->tracking_list, tracking)
> dlm_print_one_lock_resource(res);
> }
> + spin_unlock(&dlm->track_lock);
>
The locking order should be res->spinlock > dlm->track_lock.
Since here just want to print error message for issue tracking, I'm
wandering if we can copy tracking list to local first.
Thanks,
Joseph
> dlm_mark_domain_leaving(dlm);
> dlm_leave_domain(dlm);
> diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
> index aaca094..826f056 100644
> --- a/fs/ocfs2/dlm/dlmmaster.c
> +++ b/fs/ocfs2/dlm/dlmmaster.c
> @@ -584,9 +584,9 @@ static void dlm_init_lockres(struct dlm_ctxt *dlm,
>
> res->last_used = 0;
>
> - spin_lock(&dlm->spinlock);
> + spin_lock(&dlm->track_lock);
> list_add_tail(&res->tracking, &dlm->tracking_list);
> - spin_unlock(&dlm->spinlock);
> + spin_unlock(&dlm->track_lock);
>
> memset(res->lvb, 0, DLM_LVB_LEN);
> memset(res->refmap, 0, sizeof(res->refmap));
>
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