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[AUTOSEL,10/14] mm/mlock: fix potential imbalanced rlimit ucounts adjustment

Message ID 20220428154222.1230793-10-gregkh@linuxfoundation.org
State New
Headers show
Series [AUTOSEL,01/14] mm: fix invalid page pointer returned with FOLL_PIN gups | expand

Commit Message

Greg KH April 28, 2022, 3:42 p.m. UTC 
From: Miaohe Lin <linmiaohe@huawei.com>

commit 5c2a956c3eea173b2bc89f632507c0eeaebf6c4a upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/mlock.c | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/mm/mlock.c b/mm/mlock.c
index 37f969ec68fa..b565b1aac8d4 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -838,6 +838,7 @@  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;