From 7c61c35bbd6a888416e5a6de8ff8782a70d013d4 Mon Sep 17 00:00:00 2001
From: Miaohe Lin <linmiaohe@huawei.com>
Date: Fri, 29 Apr 2022 14:40:43 +0800
Subject: [PATCH] mm/z3fold: fix possible null pointer dereferencing
alloc_slots could fail to allocate memory under heavy memory pressure. So
we should check zhdr->slots against NULL to avoid future null pointer
dereferencing.
Link: https://lkml.kernel.org/r/20220429064051.61552-3-linmiaohe@huawei.com
Fixes: fc5488651c7d ("z3fold: simplify freeing slots")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/z3fold.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/mm/z3fold.c b/mm/z3fold.c
index c2260f5a58857..5d8c21f2bc592 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -940,9 +940,19 @@ static inline struct z3fold_header *__z3fold_alloc(struct z3fold_pool *pool,
}
}
- if (zhdr && !zhdr->slots)
+ if (zhdr && !zhdr->slots) {
zhdr->slots = alloc_slots(pool, GFP_ATOMIC);
+ if (!zhdr->slots)
+ goto out_fail;
+ }
return zhdr;
+
+out_fail:
+ if (!kref_put(&zhdr->refcount, release_z3fold_page_locked)) {
+ add_to_unbuddied(pool, zhdr);
+ z3fold_page_unlock(zhdr);
+ }
+ return NULL;
}
/*
--
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