diff options
| author | Hillf Danton <hdanton@sina.com> | 2021-05-18 16:46:25 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-06-18 09:58:59 +0200 |
| commit | 86fd5b27db743a0ce0cc245e3a34813b2aa6ec1d (patch) | |
| tree | 13021b412ad91c2e554b45792199371a1c1b6bab | |
| parent | 527f70f767429555648ef42664d362bd0e3b947e (diff) | |
gfs2: Fix use-after-free in gfs2_glock_shrink_scan
[ Upstream commit 1ab19c5de4c537ec0d9b21020395a5b5a6c059b2 ]
The GLF_LRU flag is checked under lru_lock in gfs2_glock_remove_from_lru() to
remove the glock from the lru list in __gfs2_glock_put().
On the shrink scan path, the same flag is cleared under lru_lock but because
of cond_resched_lock(&lru_lock) in gfs2_dispose_glock_lru(), progress on the
put side can be made without deleting the glock from the lru list.
Keep GLF_LRU across the race window opened by cond_resched_lock(&lru_lock) to
ensure correct behavior on both sides - clear GLF_LRU after list_del under
lru_lock.
Reported-by: syzbot <syzbot+34ba7ddbf3021981a228@syzkaller.appspotmail.com>
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | fs/gfs2/glock.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 9e1685a30bf8..01c41087f067 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1552,6 +1552,7 @@ __acquires(&lru_lock) while(!list_empty(list)) { gl = list_entry(list->next, struct gfs2_glock, gl_lru); list_del_init(&gl->gl_lru); + clear_bit(GLF_LRU, &gl->gl_flags); if (!spin_trylock(&gl->gl_lockref.lock)) { add_back_to_lru: list_add(&gl->gl_lru, &lru_list); @@ -1597,7 +1598,6 @@ static long gfs2_scan_glock_lru(int nr) if (!test_bit(GLF_LOCK, &gl->gl_flags)) { list_move(&gl->gl_lru, &dispose); atomic_dec(&lru_count); - clear_bit(GLF_LRU, &gl->gl_flags); freed++; continue; } |