Commit 5c2a956c authored by Miaohe Lin's avatar Miaohe Lin Committed by Linus Torvalds
Browse files

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: d7c9e99a ("Reimplement RLIMIT_MEMLOCK on top of ucounts")
Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarHugh 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1e7a8181

mm/mlock.c

+1 −0
Original line number Diff line number Diff line
@@ -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;