linux-kernel - [PATCH 3.16 078/157] block: do not leak memory in bio_copy_user

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Message-ID: <lsq.1565469607.283676874@decadent.org.uk>
Date:   Sat, 10 Aug 2019 21:40:07 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        linux-block@...r.kernel.org,
        "Jérôme Glisse" <jglisse@...hat.com>,
        "Jens Axboe" <axboe@...nel.dk>,
        "Chaitanya Kulkarni" <chaitanya.kulkarni@....com>
Subject: [PATCH 3.16 078/157] block: do not leak memory in bio_copy_user_iov()

3.16.72-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jérôme Glisse <jglisse@...hat.com>

commit a3761c3c91209b58b6f33bf69dd8bb8ec0c9d925 upstream.

When bio_add_pc_page() fails in bio_copy_user_iov() we should free
the page we just allocated otherwise we are leaking it.

Cc: linux-block@...r.kernel.org
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@....com>
Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 block/bio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/block/bio.c
+++ b/block/bio.c
@@ -1216,8 +1216,11 @@ struct bio *bio_copy_user_iov(struct req
 			}
 		}
 
-		if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
+		if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes) {
+			if (!map_data)
+				__free_page(page);
 			break;
+		}
 
 		len -= bytes;
 		offset = 0;