diff options
| author | Yiwen Jiang <jiangyiwen@huawei.com> | 2015-09-04 15:44:37 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-04 16:54:41 -0700 |
| commit | f57a22ddecd6f26040a67e2c12880f98f88b6e00 (patch) | |
| tree | d83dbca8f8bdd0e918addfd21f529f483734fc4e /fs/ocfs2/dlm | |
| parent | 743b5f1434f57a147226c747fe228cadeb7b05ed (diff) | |
ocfs2: avoid access invalid address when read o2dlm debug messages
The following case will lead to a lockres is freed but is still in use.
cat /sys/kernel/debug/o2dlm/locking_state dlm_thread
lockres_seq_start
-> lock dlm->track_lock
-> get resA
resA->refs decrease to 0,
call dlm_lockres_release,
and wait for "cat" unlock.
Although resA->refs is already set to 0,
increase resA->refs, and then unlock
lock dlm->track_lock
-> list_del_init()
-> unlock
-> free resA
In such a race case, invalid address access may occurs. So we should
delete list res->tracking before resA->refs decrease to 0.
Signed-off-by: Yiwen Jiang <jiangyiwen@huawei.com>
Reviewed-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ocfs2/dlm')
| -rw-r--r-- | fs/ocfs2/dlm/dlmmaster.c | 22 | ||||
| -rw-r--r-- | fs/ocfs2/dlm/dlmthread.c | 10 |
2 files changed, 21 insertions, 11 deletions
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c index fdf4b41d0609..46b8b2bbc95a 100644 --- a/fs/ocfs2/dlm/dlmmaster.c +++ b/fs/ocfs2/dlm/dlmmaster.c @@ -498,16 +498,6 @@ static void dlm_lockres_release(struct kref *kref) mlog(0, "destroying lockres %.*s\n", res->lockname.len, res->lockname.name); - spin_lock(&dlm->track_lock); - if (!list_empty(&res->tracking)) - list_del_init(&res->tracking); - else { - mlog(ML_ERROR, "Resource %.*s not on the Tracking list\n", - res->lockname.len, res->lockname.name); - dlm_print_one_lock_resource(res); - } - spin_unlock(&dlm->track_lock); - atomic_dec(&dlm->res_cur_count); if (!hlist_unhashed(&res->hash_node) || @@ -795,8 +785,18 @@ lookup: dlm_lockres_grab_inflight_ref(dlm, tmpres); spin_unlock(&tmpres->spinlock); - if (res) + if (res) { + spin_lock(&dlm->track_lock); + if (!list_empty(&res->tracking)) + list_del_init(&res->tracking); + else + mlog(ML_ERROR, "Resource %.*s not " + "on the Tracking list\n", + res->lockname.len, + res->lockname.name); + spin_unlock(&dlm->track_lock); dlm_lockres_put(res); + } res = tmpres; goto leave; } diff --git a/fs/ocfs2/dlm/dlmthread.c b/fs/ocfs2/dlm/dlmthread.c index 69aac6f088ad..2e5e6d5fffe8 100644 --- a/fs/ocfs2/dlm/dlmthread.c +++ b/fs/ocfs2/dlm/dlmthread.c @@ -211,6 +211,16 @@ static void dlm_purge_lockres(struct dlm_ctxt *dlm, __dlm_unhash_lockres(dlm, res); + spin_lock(&dlm->track_lock); + if (!list_empty(&res->tracking)) + list_del_init(&res->tracking); + else { + mlog(ML_ERROR, "Resource %.*s not on the Tracking list\n", + res->lockname.len, res->lockname.name); + __dlm_print_one_lock_resource(res); + } + spin_unlock(&dlm->track_lock); + /* lockres is not in the hash now. drop the flag and wake up * any processes waiting in dlm_get_lock_resource. */ if (!master) { |