linux-kernel - [PATCH AUTOSEL 4.19 41/73] block: Clear kernel memory before copying to user

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Message-Id: <20181114222207.98701-41-sashal@kernel.org>
Date:   Wed, 14 Nov 2018 17:21:35 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Keith Busch <keith.busch@...el.com>, Jens Axboe <axboe@...nel.dk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.19 41/73] block: Clear kernel memory before copying to user

From: Keith Busch <keith.busch@...el.com>

[ Upstream commit f3587d76da05f68098ddb1cb3c98cc6a9e8a402c ]

If the kernel allocates a bounce buffer for user read data, this memory
needs to be cleared before copying it to the user, otherwise it may leak
kernel memory to user space.

Laurence Oberman <loberman@...hat.com>
Signed-off-by: Keith Busch <keith.busch@...el.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 block/bio.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/bio.c b/block/bio.c
index 0093bed81c0e..41173710430c 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1261,6 +1261,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
 		if (ret)
 			goto cleanup;
 	} else {
+		zero_fill_bio(bio);
 		iov_iter_advance(iter, bio->bi_iter.bi_size);
 	}
 
-- 
2.17.1