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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,
        syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com,
        Jason Wang <jasowang@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.9 012/145] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE
Date:   Fri, 23 Feb 2018 19:25:18 +0100
Message-Id: <20180223170726.257211330@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Jason Wang <jasowang@redhat.com>

commit 6e6e41c3112276288ccaf80c70916779b84bb276 upstream.

To avoid slab to warn about exceeded size, fail early if queue
occupies more than KMALLOC_MAX_SIZE.

Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com
Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 include/linux/ptr_ring.h |    2 ++
 1 file changed, 2 insertions(+)

--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -351,6 +351,8 @@ static inline void *ptr_ring_consume_bh(
 
 static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp)
 {
+	if (size * sizeof(void *) > KMALLOC_MAX_SIZE)
+		return NULL;
 	return kcalloc(size, sizeof(void *), gfp);
 }