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| author | Hillf Danton <hdanton@sina.com> | 2021-05-18 10:46:25 +0200 |
|---|---|---|
| committer | Andreas Gruenbacher <agruenba@redhat.com> | 2021-05-31 12:03:28 +0200 |
| commit | 1ab19c5de4c537ec0d9b21020395a5b5a6c059b2 (patch) | |
| tree | 7fa57e0effbb461e2b36f5e1b6e54ef51daf6089 /fs/gfs2 | |
| parent | gfs2: Fix mmap locking for write faults (diff) | |
| download | linux-1ab19c5de4c537ec0d9b21020395a5b5a6c059b2.tar.xz linux-1ab19c5de4c537ec0d9b21020395a5b5a6c059b2.zip | |
gfs2: Fix use-after-free in gfs2_glock_shrink_scan
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>
Diffstat (limited to 'fs/gfs2')
| -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 797949e784cc..d9cb261f55b0 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1795,6 +1795,7 @@ __acquires(&lru_lock) while(!list_empty(list)) { gl = list_first_entry(list, 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); @@ -1840,7 +1841,6 @@ 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; } |