linux-kernel - [PATCH 5.7 070/244] xen/xenbus: Fix a double free in xenbus_map_ring

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Message-Id: <20200720152829.176928741@linuxfoundation.org>
Date:   Mon, 20 Jul 2020 17:35:41 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.7 070/244] xen/xenbus: Fix a double free in xenbus_map_ring_pv()

From: Dan Carpenter <dan.carpenter@...cle.com>

[ Upstream commit ba8c423488974f02b538e9dc1730f0334f9b85aa ]

When there is an error the caller frees "info->node" so the free here
will result in a double free.  We should just delete first kfree().

Fixes: 3848e4e0a32a ("xen/xenbus: avoid large structs and arrays on the stack")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Link: https://lore.kernel.org/r/20200710113610.GA92345@mwanda
Reviewed-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/xen/xenbus/xenbus_client.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index 4f168b46fbca5..786fbb7d8be06 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -693,10 +693,8 @@ static int xenbus_map_ring_pv(struct xenbus_device *dev,
 	bool leaked;
 
 	area = alloc_vm_area(XEN_PAGE_SIZE * nr_grefs, info->ptes);
-	if (!area) {
-		kfree(node);
+	if (!area)
 		return -ENOMEM;
-	}
 
 	for (i = 0; i < nr_grefs; i++)
 		info->phys_addrs[i] =
-- 
2.25.1