[PATCH v2] mm/mlock: fix potential imbalanced rlimit ucounts adjustment

Miaohe Lin
2022-03-14T06:41:37Z

user_shm_lock forgets to set allowed to 0 when get_ucounts fails. So
the later user_shm_unlock might do the extra dec_rlimit_ucounts. Fix
this by resetting allowed to 0.

Fixes: d7c9e99aee48 ("Reimplement RLIMIT_MEMLOCK on top of ucounts")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Hugh Dickins <hughd@google.com>
---
v1->v2:
correct Fixes tag and collect Acked-by tag
Thanks Hugh for review!
---
mm/mlock.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/mm/mlock.c b/mm/mlock.c
index 29372c0eebe5..efd2dd2943de 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -733,6 +733,7 @@ int user_shm_lock(size_t size, struct ucounts *ucounts)
}
if (!get_ucounts(ucounts)) {
dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
+ allowed = 0;
goto out;
}
allowed = 1;
--
2.23.0