linux-kernel - [PATCH] block: Fix potential NULL pointer dereference in __bio_crypt

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Message-ID: <20200901115921.8926-1-linmiaohe@huawei.com>
Date:   Tue, 1 Sep 2020 07:59:21 -0400
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <axboe@...nel.dk>, <ebiggers@...gle.com>, <satyat@...gle.com>
CC:     <linux-block@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH] block: Fix potential NULL pointer dereference in __bio_crypt_clone()

mempool_alloc() may return NULL if __GFP_DIRECT_RECLAIM is not set in
gfp_mask under memory pressure. So we should check the return value of
mempool_alloc() against NULL before dereference.

Fixes: a892c8d52c02 ("block: Inline encryption support for blk-mq")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 block/blk-crypto.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/blk-crypto.c b/block/blk-crypto.c
index 2d5e60023b08..046aff85cfa3 100644
--- a/block/blk-crypto.c
+++ b/block/blk-crypto.c
@@ -98,7 +98,8 @@ void __bio_crypt_free_ctx(struct bio *bio)
 void __bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask)
 {
 	dst->bi_crypt_context = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
-	*dst->bi_crypt_context = *src->bi_crypt_context;
+	if (likely(dst->bi_crypt_context))
+		*dst->bi_crypt_context = *src->bi_crypt_context;
 }
 EXPORT_SYMBOL_GPL(__bio_crypt_clone);
 
-- 
2.19.1