linux-kernel - [PATCH 1/2] drivers/scsi: Eliminate double free

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Message-ID: <Pine.LNX.4.64.0912201806360.26912@ask.diku.dk>
Date:	Sun, 20 Dec 2009 18:06:52 +0100 (CET)
From:	Julia Lawall <julia@...u.dk>
To:	James.Bottomley@...e.de, linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH 1/2] drivers/scsi: Eliminate double free

From: Julia Lawall <julia@...u.dk>

The few lines below the kfree of hdr_buf may go to the label err_free which
will also free hdr_buf.  The most straightforward solution seems to be to
just move the kfree of hdr_buf after these gotos.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@r@
identifier E;
expression E1;
iterator I;
statement S;
@@

*kfree(E);
... when != E = E1
    when != I(E,...) S
    when != &E
*kfree(E);
// </smpl>

Signed-off-by: Julia Lawall <julia@...u.dk>

---
 drivers/scsi/ses.c                  |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
index 55b034b..3c8a024 100644
--- a/drivers/scsi/ses.c
+++ b/drivers/scsi/ses.c
@@ -591,8 +591,6 @@ static int ses_intf_add(struct device *cdev,
 		ses_dev->page10_len = len;
 		buf = NULL;
 	}
-	kfree(hdr_buf);
-
 	scomp = kzalloc(sizeof(struct ses_component) * components, GFP_KERNEL);
 	if (!scomp)
 		goto err_free;
@@ -604,6 +602,8 @@ static int ses_intf_add(struct device *cdev,
 		goto err_free;
 	}
 
+	kfree(hdr_buf);
+
 	edev->scratch = ses_dev;
 	for (i = 0; i < components; i++)
 		edev->component[i].scratch = scomp + i;
--
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