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authorYiwen Jiang <jiangyiwen@huawei.com>2015-09-04 15:44:37 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-04 16:54:41 -0700
commitf57a22ddecd6f26040a67e2c12880f98f88b6e00 (patch)
treed83dbca8f8bdd0e918addfd21f529f483734fc4e /fs
parent743b5f1434f57a147226c747fe228cadeb7b05ed (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')
-rw-r--r--fs/ocfs2/dlm/dlmmaster.c22
-rw-r--r--fs/ocfs2/dlm/dlmthread.c10
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) {

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