[BUG] ocfs2/dlm: possible data races in dlm_drop_lockres_ref_done() and dlm_get_lock_resource()
From: Tuo Li
Date: Tue Jun 13 2023 - 04:00:21 EST
Hello,
Our static analysis tool finds some possible data races in the OCFS2 file
system in Linux 6.4.0-rc6.
In most calling contexts, the variables such as res->lockname.name and
res->owner are accessed with holding the lock res->spinlock. Here is an
example:
lockres_seq_start() --> Line 539 in dlmdebug.c
spin_lock(&res->spinlock); --> Line 574 in dlmdebug.c (Lock
res->spinlock)
dump_lockres(res, ...); --> Line 575 in fs/ocfs2/dlm/dlmdebug.c
stringify_lockname(res->lockname.name, ...); --> Line 493 in
dlmdebug.c (Access res->lockname.name)
scnprintf(..., res->owner, ...); -->Line 498 in dlmdebug.c
(Access res->owner)
However, in the following calling contexts:
dlm_deref_lockres_worker() --> Line 2439 in dlmmaster.c
dlm_drop_lockres_ref_done() --> Line 2459 in dlmmaster.c
lockname = res->lockname.name; --> Line 2416 in dlmmaster.c
(Access res->lockname.name)
dlm_get_lock_resource() --> Line 701 in dlmmaster.c
if (res->owner != dlm->node_num) --> Line 1023 in dlmmaster.c
(Access res->owner)
The variables res->lockname.name and res->owner are accessed respectively
without holding the lock res->spinlock, and thus data races can occur.
I am not quite sure whether these possible data races are real and how
to fix
them if they are real.
Any feedback would be appreciated, thanks!
Reported-by: BassCheck <bass@xxxxxxxxxxx>
Best wishes,
Tuo Li