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From:   Wenwen Wang <wang6495@umn.edu>
To:     Wenwen Wang <wenwen@cs.uga.edu>
Cc:     Jens Axboe <axboe@kernel.dk>,
        linux-block@vger.kernel.org (open list:BLOCK LAYER),
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] block/bio-integrity: fix a memory leak bug
Date:   Thu, 11 Jul 2019 02:27:12 -0500
Message-Id: <1562830033-24239-1-git-send-email-wang6495@umn.edu>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Wenwen Wang <wenwen@cs.uga.edu>

In bio_integrity_prep(), a kernel buffer is allocated through kmalloc() to
hold integrity metadata. Later on, the buffer will be attached to the bio
structure through bio_integrity_add_page(), which returns the number of
bytes of integrity metadata attached. Due to unexpected situations,
bio_integrity_add_page() may return 0. As a result, bio_integrity_prep()
needs to be terminated with 'false' returned to indicate this error.
However, the allocated kernel buffer is not freed on this execution path,
leading to a memory leak.

To fix this issue, free the allocated buffer before returning from
bio_integrity_prep().

Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
---
 block/bio-integrity.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/bio-integrity.c b/block/bio-integrity.c
index 4db6208..bfae10c 100644
--- a/block/bio-integrity.c
+++ b/block/bio-integrity.c
@@ -276,8 +276,10 @@ bool bio_integrity_prep(struct bio *bio)
 		ret = bio_integrity_add_page(bio, virt_to_page(buf),
 					     bytes, offset);
 
-		if (ret == 0)
+		if (ret == 0) {
+			kfree(buf);
 			return false;
+		}
 
 		if (ret < bytes)
 			break;
-- 
2.7.4