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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= <roger.pau@citrix.com>,
        Jan Beulich <jbeulich@suse.com>,
        Juergen Gross <jgross@suse.com>
Subject: [PATCH 4.9 21/29] xen/netfront: fix leaking data in shared pages
Date:   Tue,  5 Jul 2022 13:58:02 +0200
Message-Id: <20220705115606.373332495@linuxfoundation.org>
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From: Roger Pau Monne <roger.pau@citrix.com>

commit 307c8de2b02344805ebead3440d8feed28f2f010 upstream.

When allocating pages to be used for shared communication with the
backend always zero them, this avoids leaking unintended data present
on the pages.

This is CVE-2022-33740, part of XSA-403.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/xen-netfront.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -260,7 +260,7 @@ static struct sk_buff *xennet_alloc_one_
 	if (unlikely(!skb))
 		return NULL;
 
-	page = alloc_page(GFP_ATOMIC | __GFP_NOWARN);
+	page = alloc_page(GFP_ATOMIC | __GFP_NOWARN | __GFP_ZERO);
 	if (!page) {
 		kfree_skb(skb);
 		return NULL;