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mm/z3fold: fix possible null pointer dereferencing

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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: fc5488651c ("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>
This commit is contained in:
Miaohe Lin 2022-04-29 14:40:43 +08:00 committed by akpm
parent 4c6bdb3640
commit 7c61c35bbd
1 changed files with 11 additions and 1 deletions
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12
mm/z3fold.c
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@ -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;
}
/*