From: Miaohe Lin <linmiaohe@huawei.com>
Date: Tue, 22 Mar 2022 21:44:56 +0000 (-0700)
Subject: mm/mlock: fix potential imbalanced rlimit ucounts adjustment
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=5c2a956c3eea173b2bc89f632507c0eeaebf6c4a;p=uclinux-h8%2Flinux.git

mm/mlock: fix potential imbalanced rlimit ucounts adjustment

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.

Link: https://lkml.kernel.org/r/20220310132417.41189-1-linmiaohe@huawei.com
Fixes: d7c9e99aee48 ("Reimplement RLIMIT_MEMLOCK on top of ucounts")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Herbert van den Bergh <herbert.van.den.bergh@oracle.com>
Cc: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/mlock.c b/mm/mlock.c
index 25934e7db3e1..349e2cda8c50 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -839,6 +839,7 @@ 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;